Breast Conservation Research Findings

Recent research reports have highlighted that breast conservation seems to offer a survival benefit independent of measured confounders and should be given priority if both breast conservation and mastectomy are valid options. The findings have been published in JAMA Surgery.

The decision for BCS vs Mx is multifaceted. Importantly, it is influenced by:

• The degree of patient-perceived information and involvement
• Fear of cancer recurrence
• The perception that health outweighs breast retention
• The risk of reoperation in case of positive margins

These obstacles can be overcome by dedicated patient information and education, and a collaborative weighing of pros and cons by the treating clinician and the patient.

"It is striking that extensive breast surgery is more prevalent in node-positive disease despite suitability, indicating a misconception of safety, probably both from a patient and a physician perspective. In short, more extensive breast surgery does not appear to save any lives."

Previous cohort studies show better survival after breast-conserving surgery (BCS) with postoperative radiotherapy (RT) than after mastectomy (Mx) without RT. It remains unclear whether this is an independent effect or a consequence of selection bias.

Researchers undertook the current study to determine whether the reported survival benefit of breast conservation is eliminated by adjustment for two pivotal confounders: comorbidity and socioeconomic status.

This cohort study was initiated using prospectively collected national data from:

• Swedish public health care
• Nationwide clinical data from the National Breast Cancer Quality Register
• Comorbidity data from Patient Registers at the National Board of Health and Welfare
• Individual-level education and income data from Statistics Sweden

The cohort included all women diagnosed as having primary invasive T1-2 N0-2 breast cancer and undergoing breast surgery in Sweden from 2008 to 2017. Data were analyzed between August 19, 2020, and November 12, 2020. The sample population consisted of locoregional treatment comparing three groups:

• Breast-conserving surgery with radiotherapy (BCS+RT)
• Mastectomy without radiotherapy (Mx-RT)
• Mastectomy with radiotherapy (Mx+RT)

Overall survival (OS) and breast cancer–specific survival (BCSS) were the main outcomes determined before initiation of data retrieval.

Results

Among 48,986 women:

• 29,367 (59.9%) had BCS+RT
• 12,413 (25.3%) had Mx-RT
• 7,206 (14.7%) had Mx+RT

Median follow-up was 6.28 years (range, 0.01-11.70). All-cause death occurred in 6,573 cases, with death caused by breast cancer in 2,313 cases; 5-year OS was 91.1% (95% CI, 90.8-91.3) and BCSS was 96.3% (95% CI, 96.1-96.4).

Apart from expected differences in clinical parameters, women receiving Mx-RT were older, had a lower level of education, and lower income. Both Mx groups had a higher comorbidity burden irrespective of RT.

After stepwise adjustment for all covariates, OS and BCSS were significantly worse after Mx-RT (hazard ratio [HR], 1.79; 95% CI, 1.66-1.92 and HR, 1.66; 95% CI, 1.45-1.90, respectively) and Mx+RT (HR, 1.24; 95% CI, 1.13-1.37 and HR, 1.26; 95% CI, 1.08-1.46, respectively) than after BCS+RT.

"The findings of this report confirm the superiority of BCS with RT over Mx with an overall and breast cancer–specific relative survival gain of 56% to 70% in node-negative patients. This association resisted adjustment for tumor biology and status, socioeconomic background, and comorbidities. The same association was observed in lower-burden, node-positive disease, but not in women with higher nodal stage. Because there was no inferior survival for BCS in node-positive patients, this report gives no support to advocate Mx in women without specific risk factors, such as a strong family history or gene mutations."

For full article follow the link: doi:10.1001/jamasurg.2021.1438

Primary source: JAMA Surgery