Survival in stage I–III breast cancer patients by surgical treatment in a publicly funded health care system

Abstract

Background: Recent investigations of breast cancer survival in the United States suggest that patients who receive mastectomy have poorer survival than those who receive breast-conserving surgery (BCS) plus radiotherapy, despite clinically established equivalence. This study investigates breast cancer survival in the publicly funded health care system present in Alberta, Canada.Patients and methods: Surgically treated stage I-III breast cancer cases diagnosed in Alberta from 2002 to 2010 were included. Demographic, treatment and mortality information were collected from the Alberta Cancer Registry. Unadjusted overall and breast cancer-specific mortality was assessed using Kaplan-Meier and cumulative incidence curves, respectively. Cox proportional hazards models were used to calculate stage-specific mortality hazard estimates associated with surgical treatment received.Results: A total of 14 939 cases of breast cancer (14 633 patients) were included in this study. The unadjusted 5-year all-cause survival probabilities for patients treated with BCS plus radiotherapy, mastectomy, and BCS alone were 94% (95% CI 93% to 95%), 83% (95% CI 82% to 84%) and 74% (95% CI 70% to 78%), respectively. Stage II and III patients who received mastectomy had a higher all-cause (stage II HR = 1.36, 95% CI 1.13-1.48; stage III HR = 1.74, 95% CI 1.24-2.45) and breast cancer-specific (stage II HR = 1.39, 95% CI 1.09-1.76; stage III HR = 1.79, 95% CI 1.21-2.65) mortality hazard compared with those who received BCS plus radiotherapy, adjusting for patient and clinical characteristics. BCS alone was consistently associated with poor survival.Conclusions: Stage II and III breast cancer patients diagnosed in Alberta, Canada, who received mastectomy had a significantly higher all-cause and breast cancer-specific mortality hazard compared with those who received BCS plus radiotherapy. We suggest greater efforts toward educating and encouraging patients to receive BCS plus radiotherapy rather than mastectomy when it is medically feasible and appropriate.

Breast conserving therapy and mastectomy revisited: Breast cancer‐specific survival and the influence of prognostic factors in 129,692 patients

“…Our results further support the hypothesis that BCT might be the preferred choice for breast cancer patients when both BCT and mastectomy are suitable treatment options . A previous observational study that also investigated survival outcomes following both types of surgery hypothesized that the prognostic advantage of BCT over mastectomy may be related to the effects of RT as a component of BCT while early stage mastectomy patients in general receive no RT5.…”

“…A possible explanation for the differences in BCSS between the two time cohorts, apart from the difference in the applied chemotherapy regimens, is the length of follow‐up. Recurrence peaks (including local/locoregional recurrences and distant metastases) are described to occur 2, 5 and 9 years after diagnosis . Since the 2006–2012 cohort had a median follow‐up of 7 years, this cohort may have had too short follow‐up to reveal the effect of BCT and mastectomy after 7 years.…”

“…Large randomized controlled trials (RCTs) in the 1980s have shown equal survival for breast‐conserving therapy (breast‐conserving surgery plus radiation therapy, BCT) and mastectomy in early stage breast cancer . Over recent years, however, multiple observational studies have challenged this equivalence, showing superior survival for patients treated with BCT compared to those treated with mastectomy . The use of population‐based observational studies in studying treatment effects can be of additional value on outcomes obtained through RCTs.…”

Mastectomy May Be an Inferior Oncologic Approach Compared to Breast Preservation

“…Multiple randomized studies have demonstrated that breastconserving therapy (partial mastectomy plus whole breast radiation) can yield survival outcomes equivalent to those of mastectomy (1). However, newer population-based data suggest that breast cancerespecific survival and overall survival with breast-conserving therapy may actually be better than those with mastectomy (2)(3)(4)(5)(6)(7)(8). How is this possible?…”

“…We suggest that adjuvant RT may have a more important role when surgical practice evolves to reduce the volume of tissue resected during breast and axillary surgery. The integral role of adjuvant RT in breast-conserving therapy may explain why it is associated with better breast cancerespecific survival and overall survival relative to mastectomy in several recent population-based studies (2)(3)(4)(5)(6)(7)(8). This improvement in survival is strongest in earlystage subgroups (in which postmastectomy RT is seldom used) and in those with comorbiditiesdfor whom systemic chemotherapy is less often applied (2, 4, 8)dsuggesting possible multimodality interactions.…”