The NCCN establishes clinical practice guidelines for patients and health care providers on cancer treatment, including various breast cancers. These guidelines, which shape the delivery of high-quality health care, are evidence-based; they’re updated to improve health care as research reveals new findings. One such change relates to radiation therapy after mastectomy. Studies show that post-mastectomy radiation therapy (PMRT) is highly effective in women who have breast tumors that are 5 cm or less and one to three positive lymph nodes. Because of this data, the NCCN revised its treatment guidelines to encourage physicians to “strongly consider” PMRT for women in this category.
Researchers wanted to determine how the change in guidelines affect PRMT rates, and because radiated tissue often causes complications with breast reconstruction, whether rates of reconstruction in women who had PRMT declined. Using records from the National Cancer Institute’s SEER database, they retrospectively assigned 62,422 women who had mastectomy for stage I, II or III breast cancer from 2000 to 2011 into one of three groups, based on current NCCN guidelines for PMRT:
Radiation recommended: tumors >5 cm or ≥4 positive lymph nodes (15,999 women)
Radiation strongly considered: tumor ≤5 cm, 1-3 positive nodes (15,006 women)
Radiation not recommended: tumors ≤5 cm, no positive nodes (31, 837 women)
The researchers then analyzed the level of changes in PMRT and breast reconstruction during the study period. They expected PMRT rates in the study group to increase, and in fact, they did. Rates of PMRT did not change in the “PMRT recommended” and “PMRT not recommended” groups. It did, however, increase significantly, from 26.9% to 40.5% from 2007 to 2011, in the “PMRT strongly considered” group.
So what effect did that have on breast reconstruction?
Researchers expected to find declining rates of reconstruction, saying that “anticipation of PMRT may lead to delay or omission of reconstruction, which can have cosmetic, quality-of-life, and complication implications for patients.” So they were surprised to find the opposite: rates of breast reconstruction increased in all three study groups. Study authors concluded that “the rise in reconstruction rates resulted from increasing clinician comfort with irradiation of newly reconstructed breast tissue.”
Maybe. But there are probably more issues at play here; researchers didn't evaluate the type or timing of women’s breast reconstruction, so we don't know what other issues are involved. The results could simply mean that women who want reconstruction have it, whether they have PMRT or not. Part of the answer could be that more women are having tissue flap breast reconstruction, which often produces fewer complications than radiation and breast implants, so that might be a part of the answer.
Even with the new guidelines, many women still don’t know if they need radiation until their post-mastectomy pathology is available; that means that women who have mastectomy with immediate reconstruction would likely fall into one of the three study groups. Steadily climbing rates of breast reconstruction might also be part of the story here.
Another factor is that more plastic surgeons are using delayed-immediate reconstruction procedures (see blog dated 05/03/2015). For women who may need PRMT, this involves placing a tissue expander in the chest and fully inflating it immediately after mastectomy to preserve breast shape for later reconstruction with an implant or a tissue flap.
Resource: Frasier LL, Holden S, Holden T, et al. “Temporal trends in postmastectomy radiation therapy and breast reconstruction associated with changes in National Comprehensive Cancer Network Guidelines.” Oncology [published online ahead of print November 5, 2015].