Multiple-gene sequencing rapidly replaced BRCA1/2-only testing for patients with breast cancer in the community and enabled 2-fold higher detection of clinically relevant pathogenic variants without an associated increase in prophylactic mastectomy. However, important targets for improvement in the clinical utility of multiple-gene sequencing include postsurgical delay and racial/ethnic disparity in variants of uncertain significance.

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Background Re-excision is common in BCS, in part due to lack of consensus on margin definitions. A population-based sample of surgeons was used to determine current attitudes toward margin width and identify characteristics associated with margin choice. Methods Breast cancer patients treated from 2005–2007 were identified from the L.A. and Detroit SEER registries. Pathology reports were used to identify their surgeons, who were surveyed (n = 418). Response rate was 74.6% (n = 312). Mean surgeon age was 51.9 years, 17.8% were female, and the mean number of years in practice was 18.5. Results Wide variation in margin selection was noted among surgeons, and did not differ for invasive cancer and DCIS plus radiotherapy. In a T1 invasive cancer scenario, 11% of surgeons endorsed margins of tumor not touching ink (TNTI), 42% of 1–2mm, 28% of ≥5mm, and 19% >1cm as precluding re-excision. On multivariate analysis, having 50% or more of practice devoted to breast cancer independently predicted smaller margin choice (p=0.03). For a patient with a 1.4cm grade 2 ER positive DCIS without RT planned, 3% of surgeons chose TNTI, 12% 1– 2mm, 25% ≥5mm, and 61% >1cm as precluding re-excision. Breast specialization independently predicted larger margin choice (p=0.03). Gender and years in practice were not predictive of margin choice. Conclusion Wide variation in BCS margin definition exists. Variation is similar for invasive cancer and DCIS with RT, with more specialized surgeons choosing smaller margins. In DCIS without RT, more specialized surgeons favored larger margins. A standardized margin definition may significantly affect re-excision rates.

Purpose SEER registry data has been used to suggest underuse and disparities in receipt of radiotherapy. Prior studies have cautioned that SEER may underascertain radiotherapy but lacked adequate representation to assess whether underascertainment varies by geography or patient sociodemographic characteristics. We sought to determine rates and correlates of underascertainment of radiotherapy in recent SEER data. Methods We evaluated data from 2290 survey respondents with nonmetastatic breast cancer, aged 20-79, diagnosed from 6/05-2/07 in Detroit and Los Angeles (LA) and reported to SEER registries (73% response rate). Survey responses regarding treatment and sociodemographic factors were merged to SEER data. We compared radiotherapy receipt as reported by patients versus SEER records. We then assessed correlates of radiotherapy underascertainment in SEER. Results Of 1292 patients who reported receiving radiotherapy, 273 were coded as not receiving radiotherapy in SEER (“underascertained”). Underascertainment was more common in LA than in Detroit (32.0% vs 11.25%, p<0.001). On multivariate analysis, radiotherapy underascertainment was significantly associated in each registry (LA, Detroit) with stage (p=0.008, p=0.026), income (p<0.001, p=0.050), mastectomy receipt (p<0.001, p<0.001), chemotherapy receipt (p<0.001, p=0.045), and diagnosis at a hospital that was not accredited by the American College of Surgeons (p<0.001, p<0.001). In LA, additional significant variables included younger age (p<0.001), non-private insurance (p<0.001), and delayed receipt of radiotherapy (p<0.001). Conclusions SEER registry data as currently collected may not be an appropriate source for documentation of rates of radiotherapy receipt or investigation of geographic variation in the radiation treatment of breast cancer.

Additional surgery after initial lumpectomy decreased markedly from 2013 to 2015 concomitant with dissemination of clinical guidelines endorsing a minimal negative margin. These findings suggest that surgeon-led initiatives to address potential overtreatment can reduce the burden of surgical management in patients with cancer.