Breast-Conserving Surgery With Radiotherapy Demonstrates Superiority Over Mastectomy in Breast Cancer

Patients who underwent breast-conserving surgery followed by radiotherapy demonstrated improved survival over those who received mastectomy regardless of treatment with radiotherapy, according to a study published in JAMA Surgery.

Investigators launched the trial to assess the possible association of locoregional treatment with survival in a large, population-based study. In addition to examining the efficacy of breast-conserving surgery plus radiotherapy, investigators assessed the association of socioeconomic factors and comorbidities with overall survival (OS) and breast-cancer specific survival (BCSS).

“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,” Jana de Boniface, PhD, of the Department of Surgery at Capio St. Göran’s Hospital, Stockholm, Sweden, and colleagues wrote.

The prospective cohort study examined 48,986 women with breast cancer using records from national public registers in Sweden. De Boniface and colleagues gathered clinical data on the patients from the National Breast Cancer Quality Register, individual income and education data from Statistics Sweden, and data on patients’ comorbidities using patient registers at the National Board of Health and Welfare. The study focused on 3 interventions: mastectomy with radiotherapy, mastectomy without radiotherapy, and breast-conserving surgery with radiotherapy.

Patients included in the study had been diagnosed with primary invasive breast cancer from January 2008 to December 2017, all of whom underwent surgery within that time period. Known tumor sizes were upwards of 50 mm, with involvement in no more than 10 nodes. Most women (59.9%; n = 29,367) received breast-conserving surgery and radiotherapy. Moreover, slightly more than a quarter (25.3%; n = 12,413) underwent mastectomy with no radiotherapy and 14.7% (n = 7206) received mastectomy plus radiotherapy.

Data from the trial indicated that in all patients, there was a 5-year OS rate of 91.1% (95% CI, 90.8%-91.3%) and a 10-year OS rate of 79.5%. The 5- and 10-year BCSS rates were 96.3% (95% CI, 96.1%-96.4%) and 93.1%, respectively.

Patients who received breast-conserving surgery and radiotherapy were between 40 to 74 years old with smaller tumors and less nodal involvement vs those who received mastectomy and radiotherapy. Moreover, those in the mastectomy plus radiotherapy cohort more commonly received neoadjuvant therapies, adjuvant chemotherapy, and targeted agents, as well as had larger tumors and more nodal involvement.

At a median follow-up of 6.28 years (range, 0.01-11.70), 6573 women died, 35.2% of whom (n = 2313) died of breast cancer. When patients were stratified based on prognostic cohort, those who received mastectomy plus radiotherapy had an association with lower BCSS with a clear indication for radiotherapy. Moreover, the cohort also had the lowest survival across all prognostic cohorts.

Women who underwent mastectomy without radiotherapy were older, less educated, and had a lower income compared with those who received other treatments, the investigators reported. All women who received mastectomy had a greater burden of comorbidities than those who underwent breast-conserving surgery.

“There are complex interactions between breast cancer survival, socioeconomic status, and comorbidity. Individuals with a lower socioeconomic status present with more advanced disease, have a lower adherence to mammography screening, are less likely to receive chemotherapy, and have inferior survival rates,” the authors of the study wrote.

After the investigators adjusted for covariates, they reported that both groups of women who underwent mastectomy demonstrated poorer OS and BCSS compared with those who received breast conservation surgery and radiotherapy (HR, 1.79; 95% CI, 1.66-1.92 and HR, 1.66; 95% CI, 1.45-1.90, respectively, for mastectomy without radiotherapy; HR, 1.24; 95% CI, 1.13-1.37 and HR, 1.26; 95% CI, 1.08-1.46, respectively, for mastectomy with radiotherapy).

The study was limited by the lack of confounding factors such as body mass index, whether patients smoked, and the possibility of underestimated comorbidities. Further, considering the potential for late recurrence, the investigators noted that follow-up time was relatively short. Despite this, de Boniface and colleagues concluded that more extensive breast surgery did not appear to save any lives.

“The findings of this report confirm the superiority of breast-conserving surgery with radiotherapy over mastectomy with an OS and relative BCSS gain of 56% to 70% in node-negative patients. This association resisted adjustment for tumor biology and status, socioeconomic background, and comorbidities,” the investigators concluded.

Reference

de Bonfice J, Szulkin R, et al. Survival after breast conservation vs mastectomy adjusted for comorbidity and socioeconomic status a Swedish national 6-year follow-up of 48,986 Women. JAMA Surg. Published online,May 5, 2021. doi:10.1001/jamasurg.2021.1438.