Author: By Lynda Williams, Senior medwireNews Reporter
medwireNews: Breast-conserving surgery (BCS) with radiotherapy (RT) offers better survival outcomes than mastectomy with or without radiation for women with primary invasive breast cancer, indicates an analysis of Swedish patients accounting for differences in comorbidity and socioeconomic status.
“This report casts additional doubt on the practice to offer mastectomy to patients who are suitable candidates for breast conservation”, write Jana de Boniface, from Capio St Göran’s Hospital in Stockholm, Sweden, and co-authors in JAMA Surgery.
The investigators analysed information for all 48,986 women who underwent surgery in Sweden between 2008 and 2017 for primary invasive T1–T2, N0–N2 breast cancer, with a median follow-up of 6.28 years.
Overall, 6573 patients died, including 2313 deaths from breast cancer, giving 5-year rates of overall survival (OS) and breast cancer-specific survival of 91.1% and 96.3%, respectively.
The researchers report that women who underwent mastectomy without RT were older, had fewer years of education and a lower income than those who underwent BCS plus RT, and patients who had a mastectomy with or without RT had a higher burden of comorbidity than their BCS plus RT counterparts.
OS was significantly worse among patients who underwent mastectomy, with or without RT, than among the BCS cohort, with hazard ratios (HRs) for death of 1.24 and 1.79, respectively, after accounting for age, calendar year, region of residence, Nottingham grade, prognostic group, tumour subtype, education, family income, country of birth and Charlson Comorbidity Index a year before surgery.
Similarly, breast cancer-specific surgery was significantly poorer among the two mastectomy groups than the BCS group, with corresponding HRs for breast cancer-related death of 1.26 and 1.66, after adjusting for all the stated factors.
However, Jana de Boniface et al say that when patients were further assessed by prognosis, “the associations varied substantially”.
They cite significantly poorer OS and breast cancer-specific survival among patients who underwent mastectomy without RT versus those given BCS plus radiation, except for patients with T1N1 disease for whom there was only a significant association with OS.
Patients with T1N0, T1N1 and T2N0 disease were significantly more likely to die following mastectomy plus RT than BCS plus RT, but this was not true for T1N2 disease. There were no significant survival associations for mastectomy plus RT versus BCS plus RT for T2N1 or T2N2 disease, although both subgroups had “moderately increased” point estimates for OS, the researchers say.
Summarising that BCS plus RT was superior to either mastectomy option for patients with node-negative patients and those with lower burden, node-positive disease, they continue that “[b]ecause there was no inferior survival for BCS in node-positive patients, this report gives no support to advocate [mastectomy] in women without specific risk factors, such as a strong family history or gene mutations.”
Lisa Newman, from Weill Cornell Medicine in New York, USA, writes in an invited commentary that the study findings may provide “evidence supporting the hypothesis that radiation induces secondary abscopal antitumor effects” that offer an advantage over lumpectomy alone.
However, noting that there was a “disproportionally high frequency of T1 and hormone receptor-positive/[HER2]-negative tumors in the BCS compared with mastectomy subsets”, the commentator says that the findings could also indicate that there was “a significant subset of potentially overtreated cases within the BCS group.”
Lisa Newman concludes: “Regardless of the interpretation chosen for the outcome patterns observed in this study, one fact cannot be disputed: BCS is safe and effective management in early-stage breast cancer.”
References
de Boniface J, Szulkin R, Johansson ALV. 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; Advance online publication 5 May 2021. doi:10.1001/jamasurg.2021.1438
Newman LA. Safety of breast-conserving surgery in breast cancer and risk of overtreatment vs undertreatment. JAMA Surg; Advance online publication 5 May 202. doi:10.1001/jamasurg.2021.1450
medwireNews (www.medwireNews.com) is an independent medical news service provided by Springer Healthcare. © 2021 Springer Healthcare part of the Springer Nature group