preserves all of a woman’s breast skin, including the nipple and areola. Essentially, it allows women to keep the part of the breast that we actually see—the skin, nipple and areola—while the breast tissue is removed and replaced with either a breast implant or a flap of her own tissue.
Whether women have mastectomy to prevent or treat breast cancer, most are candidates for nipple-sparing mastectomy. Individuals with very large tumors or tumors in or close to the nipple are not candidates for nipple-sparing procedures. Women with moderate to severe breast ptosis
(sagging) are also routinely advised against nipple-sparing mastectomy. Ptosis develops when aging or gravity causes the breasts to sag (breast tissue contains no supportive muscle). Ptosis can also occur after pregnancy, breastfeeding or significant weight loss. Smoking also accelerates ptosis because it erodes skin elasticity.
In round, non-sagging (or minimally sagging) breasts, the retained nipple is more likely to end up where it should be after reconstruction: in the center of the new breast. Large, pendulous breasts tend to be low-hanging and oblong rather than round, with nipples that are positioned far south of center. They make nipple-sparing mastectomy difficult, because of the likelihood that the nipples cannot be appropriately positioned on the new breast.
It’s mostly a problem of excess skin.
Ptotic breasts hang low on the chest, with nipples that point downward.
Patients and surgeons don’t face the same issue when a traditional mastectomy is performed, because much of the excess breast skin that encloses the droopy breast can be removed along with the nipple and areola. But what do you do with all that excess skin when a nipple-sparing mastectomy leaves the nipple, areola and breast skin intact, and how do you elevate the nipple so that it is centered on the new breast?
It’s a problem that presents technical and aesthetic surgical challenges.
A recently-published study in the journal Plastic and Reconstructive Surgery
introduces a new procedure that is specifically designed to provide nipple-sparing mastectomy as an option for women with ptotic breasts, as long as an oncologic reason doesn’t preclude them from having nipple-sparing mastectomy.
NSM + tissue flap + breast lift = NSM for low-hanging breasts
The new technique combines nipple-sparing mastectomy, perforator flap reconstruction
and breast lift procedures. First, a breast surgeon who is experienced with nipple-sparing mastectomy removes the breast tissue through a periareolar (around the areola) incision. Then the reconstructive surgeon performs a perforator flap reconstruction, restoring volume from missing breast tissue with fatty tissue from a patient’s hip or abdomen. Finally, a full breast lift is performed on the reconstructed breast: the transferred flap of tissue is tightened and reshaped, excess skin is removed, and the incision is closed. The result is a newly-recreated breast with a correctly positioned natural nipple and areola.
Like all reconstructive surgeries, the new procedure requires appropriate surgical skill and experience to preserve adequate blood flow to the nipple. It’s a new concept and a new technique that will probably take a while to catch on. -------------
DellaCroce J, Blum CA, Sullivan S K, et al. "Nipple Sparing Mastectomy and Ptosis: Perforator Flap Breast Reconstruction Allows Full Secondary Mastopexy with Complete Nipple Areolar Repositioning." Journal of Plastic and Reconstructive Surgery,
July 2015; Vol. 136, Issue 1: p. 1e–9e.
Surgeons routinely caution women who smoke or carry extra weight about the increased possibility of post-op complications from breast reconstruction. Any major surgery—not only breast reconstruction—has the potential for problems, but smoking and extra weight complicate matters even more, increasing the likelihood that problems may develop. Smoking
If you smoke, most surgeons will require you to quit for several weeks before and after your breast reconstruction procedure. It’s for your own good: smoking compromises your respiratory capability and overall health; inhaled carbon monoxide and nicotine from tobacco smoke restrict blood flow and increases the chances of infection, excessive scarring, and poor wound healing. Smokers are also more likely to experience necrosis, or tissue death, in the reconstructed breast. This is particularly problematic with tissue flap reconstruction when a portion or all of the new breast dies because it doesn’t get adequate blood and oxygen. The good news:
Women who stop smoking at least three weeks prior to surgery have no greater complications than non-smokers who have the same surgery.Overweight or obese
Being obese doesn’t automatically limit your ability to have immediate or delayed breast reconstruction. In fact, obese women are just as likely to be satisfied with their reconstructive results as women who are thinner. If you are obese, however, particularly if you have a BMI of 35 or higher, you are more likely to develop infection, delayed wound healing, clotting complications and other problems, regardless of the type of reconstruction. The odds of developing problems are even greater if your BMI is 40 or more. Three recent studies confirm what we already knew
While many studies (and surgeon’s experience with patient outcomes) have shown that smokers and heavier women generally can expect more problems after breast reconstruction, research published this year shows that both groups also more frequently need revision surgery (a separate surgery to correct cosmetic issues or healing problems). Researchers concluded that:
The bottom line:
- Among women who had bilateral immediate, delayed or immediate-delayed breast reconstruction, those who had a BMI greater than 30 were twice as likely to experience a complication as those with a normal BMI. A higher Body Mass Index was also significantly related to infection, seroma, hematoma and delayed wound healing.
- Among 2,899 women who had breast reconstruction with any type of tissue flap, 18.2% of smokers developed wound complications compared to 8.4% non-smokers.
- Considering all free autologous (tissue flap) reconstructions at a single institution between 2005-2011, women who smoked or were obese suffered more delayed wound healing (operative wounds requiring dressing changes for longer than 3 weeks) compared to other non-smokers and thinner women who had similar reconstructive surgeries.
It makes good sense to do your very best to lose weight and stop smoking before your surgery. Under the very best conditions, recovery from mastectomy
and breast reconstruction is physically and emotionally taxing. You'll reap the benefits of preparing yourself for the ordeal--being in the best possible shape (that includes a body that isn't compromised by the effects of nicotine or excess weight)--so that you can minimize the effects of your surgery and bounce back to your "normal" as soon as possible.
Chung CU, Wink JD, Nelson JA, et al. “Surgical Site Infections after Free Flap Breast Reconstruction: An Analysis of 2,899 Patients from the ACS-NSQIP Datasets.” Journal of Reconstructive Microsurgery
Apr 24, 2015. [Epub ahead of print]
Nelson JA, Chung CU, Fischer JP, et al. “Wound healing complications after autologous breast reconstruction: a model to predict risk.” Journal of Plastic, Reconstructive & Aesthetic Surgery
(2015); 68(4): pp. 531-9.
Mirzabeigi MN, Wilson AJ, et al. “Predicting and managing donor-site wound complications in abdominally based free flap breast reconstruction: improved outcomes with early reoperative closure.” Plastic & Reconstructive Surgery
(2015); 135(1): pp. 14-23.
Most people know that Botox®
—the most popular minimally invasive cosmetic procedure—is most commonly used to erase facial wrinkles. Derived from the bacterium Clostridium botulinum
, Botox is a neurotoxin; it works by impeding nerve impulses that cause muscle contractions. Injections into the forehead or the “crows feet” area beyond the eye eliminates wrinkles for a few months, while Botox injected into the underarm temporarily eliminates excessive perspiration. It is also used to curtail overactive bladders.
What most people do not know is that Botox is also a very effective painkiller that some physicians now use to relieve the pain of migraine headaches and other types of chronically painful conditions. New research shows that it may also ease the discomfort many women experience with tissue expanders, and shorten the overall expansion timeline.
For many women, the pressure exerted by tissue expanders
on the pectoralis chest muscle can be quite uncomfortable, and even painful. Botox relaxes the muscle, reducing discomfort and generally creating a more tolerable experience as a woman proceeds through the stages of expanding the pocket behind the muscle to make room for a breast implant.
A small study at Loma Linda University involved 30 patients who had mastectomies with immediate reconstruction
with tissue expanders or acellular dermal matrix
. Half of the patients received 40 units of Botox serially injected directly into their pectoralis muscles; the remaining participants—the control group—received four serial injections of sodium chloride (saline).
Compared to women who received the placebo (the saline), women who received the neurotoxin benefited in three ways:
· They reported less pain and muscle spasms.
· They completed the expansion process sooner because they were able to tolerate more saline during office “fill” visits: a mean of 98 cc per fill compared to 54 cc in the placebo group.
· They required fewer opioids and valium after the first post-op week (subsequent use of oral NSAIDs was about the same in both groups).
The two groups were of similar age, with no significiant differences between initial fills and expander sizes. No complications or side effects from the neurotoxin were reported, and complication rates for seroma, infection, skin necrosis, expander loss and hematoma did not vary.
This study echoes the results of various other small studies over the past few years, but the use of Botox is by no means standard with tissue expansion for breast reconstruction. Although Botox is FDA-approved for various applications, its use in breast reconstruction is “off label,” meaning it might be helpful but that is not specifically its approved use. (That’s why its use in breast reconstruction may not be covered by insurance.)
A larger-scale clinical study is currently underway at the Mayo Clinic; its results may have a more profound influence on whether Botox becomes more common during tissue expansion, and whether or not insurance will cover it.
Source: Gabriel A, et al. “The efficacy of botulinum toxin a in post-mastectomy breast reconstruction: a pilot study.” Aesthetic Surgery Journal
(2015) 35(4): p. 402-9.
For women who plan to have immediate breast reconstruction,
traditional skin-sparing mastectomy
removes the breast tissue, nipple and areola. In an optional procedure, new nipples can then be recreated on the reconstructed breasts.
is a newer, more conservative option for women who have immediate breast reconstruction
; it preserves all of the breast skin, including the nipple and areola. Many women feel that this allows them to keep a small part—and from an emotional perspective, perhaps the most important part—of their natural breasts. Here's what you should know about nipple-sparing mastectomy:
- It’s safe. Numerous studies over the past decade have shown that nipple-sparing mastectomy is a safe option for the right candidates. A Stanford University School of Medicine analysis of 19 previous studies involving more than 5,000 mastectomy patients concluded that nipple-sparing procedures result in similar rates of recurrence and survival compared to skin-sparing mastectomy procedures that remove the nipple.
- Not all women are candidates. Women with a small early-stage tumor that is not in the skin or close to the nipple may be eligible for nipple-sparing mastectomy. It is also viable for women who choose prophylactic mastectomy to reduce their unusually high risk of developing breast cancer due to a strong family history or inherited genetic mutation (like Angelina Jolie Pitt). Nipple-sparing procedures are not recommended for women who have multiple breast tumors close to the skin or nipple (although some experts consider this is acceptable if the tumors are not in close proximity to the nipple). The entire nipple and areola are removed if the tissue beneath the nipple is found to contain cancerous cells. Positioning nipples on the reconstructed breast can also be an issue; they may not be centered ideally if the reconstructed breasts are smaller or larger than the natural breasts.
- It facilitates cosmetically superior breast reconstruction. Because the breast skin, areola and nipple are retained, and the mastectomy scar is usually hidden under the breast or in the areola, your reconstructed breasts will likely appear as natural and as good or better than your own breasts before mastectomy. Although what is under the skin is different—breast tissue is replaced with breast implants or your own natural tissue—outwardly, the exterior of the breast appears intact and virtually unchanged.
- Incision placement is critical. Traditional skin-sparing mastectomy is performed through an elliptical incision around the nipple and areola. In a nipple-sparing mastectomy, a shorter incision is made just below the nipple—requiring the breast surgeon to remove the same amount of tissue through this smaller incision. Some women, particularly those with very large or sagging breasts, may need an additional horizontal incision from the nipple towards the arm, or an additional vertical incision from the nipple towards the bottom of the breast.
- The retained nipple may be different. Nipple sensation after nipple-sparing mastectomy varies, but it is usually considerably reduced because the fine nerves and small muscle fibers that trigger sensation and response are cut when breast tissue is removed. After nipple-sparing mastectomy, nipples may also flatten or look differently.
- Not all surgeons are qualified. Nipple-sparing mastectomy is now more common, but it is by no means standard. Many breast surgeons do not have the training or experience to perform the procedure, which is technically more demanding than other mastectomy procedures. Surgeons must be able to carefully remove the underlying tissue without compromising the blood supply the nipple needs to survive; leaving behind too much breast tissue increases the risk of another diagnosis.
Ideally, breast reconstruction is performed at the same time as mastectomy, but sometimes that isn’t always possible. Some women are undecided about reconstruction at the time of their mastectomy, while others prefer to forego any further surgery, but change their minds months or years later, and then decide to pursue delayed reconstruction. In some cases, oncologists may recommend that certain individuals, especially those with underlying health conditions that may delay healing, postpone reconstruction. Immediate planning for delayed breast reconstruction
If your oncologist recommends a mastectomy to treat invasive breast cancer, you may or may not also need radiation therapy after the surgery, depending on the stage of your tumor and lymph node involvement. Unfortunately, it isn't always clear if radiation therapy will be needed until post-mastectomy pathology results are available. Under these circumstances, many surgeons advise against immediate breast reconstruction
if there is a possibility you may need radiation treatments.
If you have your heart set on immediate reconstruction with a breast implant or a flap of your own tissue, delaying your reconstruction can be a hard pill to swallow, because you will wake up with a flat chest and miss out on the advantages of immediate breast reconstruction. Delayed-immediate reconstruction
is a unique approach to this issue. It recognizes the potential need for radiation therapy and also provides the aesthetic advantages of immediate reconstruction. As soon as the breast tissue is removed, a tissue expander
is positioned under the chest muscle, and fully inflated to preserve your breast shape and skin for later reconstruction. After your mastectomy, if it turns out that you don’t need radiation after all, you can proceed with reconstruction, exchanging the expander for an implant or swapping it for an autologous tissue flap
of your own skin, fat and/or muscle.
If you do need radiation therapy, the tissue expander can be deflated and left in place, and then later reinflated when your radiation is completed. (Deflating the expanders also addresses the concern that immediate reconstruction may interfere with the delivery of radiation.) Several months later, you can proceed with tissue flap reconstruction—implants aren’t generally advised after radiation because of the high potential for complications.
Misfortune sometimes spurs innovation. One example for women who have breast reconstruction after mastectomy is an improved surgical bra that is practical and comfortable, thanks to one woman’s personal post-op experience and the desire to make the recovery process easier for all women who have breast reconstruction.
While wearing a surgery bra as she recovered from a double mastectomy and breast reconstruction, radiation oncologist Dr. Elizabeth Chabner Thompson considered how outdated compression garments could be improved upon.
Realizing that the design of surgical bras had remained unchanged since the 1970s, Thompson surveyed plastic surgeons and patients to confirm what was needed: surgical bras that not only provided adequate compression, but were also more comfortable and definitely more attractive at a time when women need to heal and feel good about themselves. Thompson then set out to develop a product that would satisfy these goals.
Wearing some type of compression garment to promote healing is recommended after most major breast surgeries: augmentation, breast lift, breast reduction, and breast reconstruction. Surgical bras promote healing by exerting constant mild pressure on the new breast; this reduces post-operative swelling and bruising, and supports the desired position of the reconstructed breast. Surgical bras are important after any type of breast reconstruction. They gently hold breasts created with autologous tissue flaps
in place, and they are particularly helpful for women who have reconstruction with breast implants
, because a surgical bra stabilizes the implant in position from the side and bottom while the pocket heals.
After breast reconstruction, a surgical bra is worn 24/7 (except while showering) for several weeks until the plastic surgeon determines that you have healed sufficiently to progress to a normal bra (or none at all if you prefer).
The result of Dr. Thompson’s efforts is the Elizabeth Pink Surgical Bra™, designed with both the surgeon and patient in mind. The pink, front-closing bra features:
- appropriate support compression.
- a Velcro front closure.
- durable, soft fabric that is kind to sensitive skin.
- adjustable padded shoulder straps for a comfortable fit.
- side openings and small rings that hold annoying-but-necessary surgical drains in place against the body.
- comfort without chafing.
Based on the instructions of individual plastic surgeons, many hospitals provide a specific type of surgery bra; some surgeons instruct patients to purchase their own garment and bring it to the hospital on the day of surgery. Numerous hospitals now provide the Elizabeth Pink Surgical Bra to their breast reconstruction patients. The bra is also available from Amazon and other online retailers, including Dr. Thompson’s own company, BFFL
, which develops products that help patients to recover from surgery and other medical treatments in comfort and with dignity.
Always follow your plastic surgeon’s instructions regarding use of surgical bras, how long you should wear them, and other recommendations for your recovery.
Women who are diagnosed with ductal carcinoma in situ (DCIS) frequently have lymph nodes removed during breast cancer surgery, even though medical guidelines recommend against it.
Studying the health records of 35,591 DCIS patients who were treated with either lumpectomy or mastectomy between 2006 and December 2012, researchers discovered that 29% of the women had lymph nodes removed during surgery: 84 had sentinel node biopsy (SLNB), while 16% had axillary lymph node dissection (ALND). SLNB removes one or two underarm lymph nodes; ALND removes several or all underarm lymph nodes.
Sampling lymph nodes is standard-of-care to stage the progress of invasive breast cancers: invasive ductal carcinoma, invasive lobular carcinoma and inflammatory breast cancer. Lymph nodes are removed and examined microscopically to help to determine whether the cancer has progressed beyond the breast, and the best treatment protocol.
Nationally recognized guidelines of both the American Society of Clinical Oncology and the National Comprehensive Cancer Network recommend against lymph node dissection in women who have DCIS that is treated with lumpectomy (the guidelines are less clear for DCIS-related mastectomy). No benefit has been associated with lymph node removal related to non-invasive DCIS, which typically remains within the breast. Guidelines recommend SLNB only when the suspicion of invasive breast cancer is high or when invasive breast cancer is discovered during surgery—as it is in about a fourth of women with DCIS who were originally diagnosed by a core biopsy.
In this study, researchers concluded that:
- 29% of the women studied had lymph nodes removed: 84.2% by sentinel lymph node biopsy (SLNB) and 15.8% by full axillary lymph node dissection (ALND).
- Among women who had mastectomy, 48% had SLNB and 15.2% had ALND.
- Among women who had lumpectomy, 16.7% had SLNB and 1% had ALND.
The study database reflected practices at more than 600 hospitals across the country, indicating that the trend is widespread. Most physicians included in the study were general surgeons; fewer than 5% were surgical oncologists. Surgeons who performed lumpectomy less often were more likely to perform some type of lymph node removal compared to high-volume surgeons—95% of studied mastectomies were performed by surgeons who operated for DCIS only once or twice a year. Why the concern?
What is most disturbing about this study’s findings is how often lymph nodes were removed from DCIS patients, despite nationally recognized guidelines to the contrary. Aside from an additional 2-3” incision, numbness in the armpit, increased risk for infection, and added time under general anesthesia, the issue is significant for another reason. Removing lymph nodes frequently compromises the lymph system, which carries excess fluids and bodily debris away from the tissues. Removing lymph nodes can impair this functionality, leading to lymphedema, mild to pronounced swelling that results when fluids don’t drain adequately and back up in the tissues.
The risk for lymphedema rises with the number of lymph nodes removed; sentinel node biopsy carries less risk of disrupting normal lymph function than a full axillary dissection. Once lymphedema develops, it becomes a lifelong condition that must be carefully managed to keep symptoms from becoming severe.
If you’ve been diagnosed with DCIS, be sure to discuss the extent of your surgery with your physician.
Reference: Coromilas E, Wright JD, Huang Y, et al. "The influence of hospital and surgeon factors on the prevalence of axillary lymph node evaluation in ductal carcinoma in situ." Journal of the American Medical Association Oncology
(2015); DOI: 10.1001/jamaoncol.2015.0389.
Once considered by Western medicine as a wacky approach to healing, acupuncture is now recognized by physicians (and most health care insurers) as a credible and effective treatment for symptoms of many types of health issues.
Studies show that acupuncture can relieve numerous types of pain, including back pain, chronic myofascial (facial) pain, neck pain, osteoarthritis in the knee, and even pain in the muscles and joints. A new study from the Mayo Clinic has found that acupuncture effectively reduces anxiety and pain after mastectomy
and breast reconstruction
Twenty breast cancer patients who had mastectomy with or without breast reconstruction participated. Needles were applied by a licensed acupuncturist with a Master’s degree level of training. For purposes of the study, a set protocol of 10 acupuncture points outlined by Traditional Chinese Medicine was used to address post-operative headache, nausea, vomiting, gastrointestinal pain, and musculoskeletal pain. Other acupuncture points also induced a calming effect to reduce patient anxiety.
All study participants were satisfied with post-op acupuncture and considered it to be worthwhile.
Women who participated in the study were taking either tamoxifen or anastrozole, anti-estrogen therapy to treat breast cancer; these anti-estrogens have a tendency to cause hot flashes, which can be frequent and strong. After 12 treatments over four weeks based on Traditional Korean Medicine acupuncture, all of the study participants reported a 70 to 95 percent reduction of the intensity of hot flashes, and overall, fewer hot flashes. In addition, the total number of hot flashes per patient reduced significantly.
Researchers concluded that acupuncture “significantly improves symptoms of postoperative pain, anxiety, and tension, and demonstrates a trend toward improved postoperative relaxation
.” Researchers also noted that “acupuncture can be integrated into a busy postsurgical clinical practice
” and “acupuncture may be an important intervention in the postoperative setting for breast cancer patients
Study reference: Mallory MJ, Croghan KA, Sandhu NP., et. al. "Acupuncture in the Postoperative Setting for Breast Cancer Patients: A Feasibility Study." The American Journal of Chinese Medicine
43, no. 01 (2015): p. 45-56.
Women who are 65 or older are often thought to be at more risk for complications after breast reconstruction, but a new study shows that isn’t necessarily the case.
Analyzing records for 40,769 women who had unilateral mastectomy between 2005 and 2012, researchers identified 15,093 women who were age 65 or older at the time of their surgery; almost 11% of these older women had breast reconstruction, compared to 39.5% of mastectomy patients who were younger than age 65.
When researchers compared 30-day complication rates between the two age groups, they found:
- complication rates were similar among women who had reconstruction with breast implants.
- for the most part, rates of post-surgical complications after autologous tissue flap reconstruction (with a woman's own natural tissue)—longer hospital stays, more frequent complications, and more re-operations—was similar: about 7% of the older women developed post-surgical complications after breast reconstruction, compared to about 5% of younger women.
- women in the 65+ group who had autologous reconstruction were more likely to suffer venous thromboembolism than their younger counterparts.
Venous thromboembolism (VTE) is a blood clot that forms in the leg or lung that breaks loose and travels in the blood. Overall, the rate of VTE among women who had autologous breast reconstruction was just 1%. Women who were 65 and older developed VTE 4 times more often than their younger counterparts; women between ages 70 and 75 developed the same problem 6 times more often.
Study authors suggested that, "Older patients should be counseled that their age does not confer an increased risk of complications after implant-based post-mastectomy breast reconstruction. However, they should be counseled that their age may confer an increased risk of VTE.”
The somewhat higher risk of VTE doesn’t necessarily preclude older women from having autologous breast reconstruction, but it does indicate that more precautions, such as the use of blood-thinning medications, should be taken with older women.
Source: Butz DR, Lapin B, Yao K, et al. “Advanced age is a predictor of 30-day complications after autologous but not implant-based postmastectomy breast reconstruction.” Plastic and Reconstructive Surgery. 2015 Feb; 135(2):253e-61e.
The National Comprehensive Cancer Network, a consortium of the nation’s leading cancer experts, and the American Society for Clinicial Oncology set national guidelines for treating various cancers. Both groups recommend post-mastectomy radiation therapy for women with locally advanced breast cancer (cancer cells in 4 or more lymph nodes). Radiation is a crucial part of treatment for these women, because it greatly reduces recurrence and improves survival.
A new study, however, shows that only 65 percent of women who meet these guidelines actually have recommended radiation.
Using the National Cancer Data Base, researchers at Louisiana State University examined the medical records of 56,990 women who were diagnosed and treated for with N2/N3 breast cancers between 1998 and 2011. They were surprised to find that 35 percent of the women did not have recommended radiation after mastectomy; the study authors had expected a much higher rate of compliance.
But why wouldn’t women who are at high risk for recurrence and potentially life-threatening consequences follow through with a recommended treatment? None of the following factors seemed to independently influence compliance or noncompliance:
- average age was 58 years
- 96% had health insurance
- 98% resided in urban communities
- 83% had no co-morbidities (medical conditions that would preclude having radiation)
- 82% received chemotherapy
- 81% were Caucasian
- 59% were from a comprehensive community cancer programs
Only three factors were associated with compliance: being alive 30 days after surgery, being readmitted to the hospital within 30 days of surgery, or having chemotherapy (women who were treated with chemotherapy were 5.4 times more likely to have radiation therapy). These were statistical factors—none of the women were actually interviewed. The researchers could not tell from the medical records whether patients were unaware of their need for radiation therapy, if they refused it, or what their reasoning might be, indicating a need to additional research.
Source: Chu QD, Caldito G, Miller JK, et al. “Postmastectomy radiation for n2/n3 breast cancer: factors associated with low compliance rate.” Presented at the Southern Surgical Association 126th Annual Meeting, Palm Beach, FL, November 30–December 3, 2014. (http://www.journalacs.org/article/S1072-7515%2815%2900025-3/abstract