The addition of radiotherapy to breast-conserving surgery improves survival for elderly patients with early breast cancer

Omission of Radiotherapy in Women >60 Years Old After Breast Conserving Surgery for Breast Cancer is Non-Inferior in Terms of Local Recurrence: A Retrospective Cohort Study

Objective

Local recurrence rate may show no significant differences between women aged 60 and older who receive breast-conserving surgery followed by radiotherapy and those in the same age group who undergo breast-conserving surgery without subsequent radiotherapy.

Materials and Methods

Retrospective cohort study from a single practice with median follow-up time 44 months (interquartile range: 16, 82), comparing women older than 60 years old at diagnosis of breast cancer, treated with breast conserving surgery and either receiving or not receiving radiation therapy postoperatively. The primary endpoint was local recurrence difference between the two groups.

Results

Local recurrence did not differ significantly between the two groups in terms of radiotherapy or not [odds ratio (OR) 0.96, 95% confidence interval (CI) 0.89-1.02, Fisher's exact test p = 0.388], nor between two age groups with cut-off at 65 years of age (OR: 0.99, 95% CI 0.92-1.07, Fisher's Exact test p = 0.6). Local recurrence also did not differ when subgroups of age (60-65 years and >66 years) were considered. All patients received 5 years of hormonal therapy.

Conclusion

Omission of radiotherapy in selected patients is not inferior to radiotherapy after breast conserving surgery in terms of preventing local recurrence.

Molecular subtypes of breast cancer predicting clinical benefits of radiotherapy after breast-conserving surgery: a propensity-score-matched cohort study

BACKGROUND

Based on the molecular expression of cancer cells, molecular subtypes of breast cancer have been applied to classify patients for predicting clinical outcomes and prognosis. However, further evidence is needed regarding the influence of molecular subtypes on the efficacy of radiotherapy (RT) after breast-conserving surgery (BCS), particularly in a population-based context. Hence, the present study employed a propensity-score-matched cohort design to investigate the potential role of molecular subtypes in stratifying patient outcomes for post-BCS RT and to identify the specific clinical benefits that may emerge.

METHODS

From 2006 to 2019, the present study included 59,502 breast cancer patients who underwent BCS from the Taiwan National Health Insurance Research Database. Propensity scores were utilized to match confounding variables between patients with and without RT within each subtype of breast cancer, namely luminal A, luminal B/HER2-negative, luminal B/HER2-positive, basal-like, and HER2-enriched ones. Several clinical outcomes were assessed, in terms of local recurrence (LR), regional recurrence (RR), distant metastasis (DM), disease-free survival (DFS), and overall survival (OS).

RESULTS

After post-BCS RT, patients with luminal A and luminal B/HER2-positive breast cancers exhibited a decrease in LR (adjusted hazard ratio [aHR] = 0.18, p < 0.0001; and, 0.24, p = 0.0049, respectively). Furthermore, reduced RR and improved DFS were observed in patients with luminal A (aHR = 0.15, p = 0.0004; and 0.29, p < 0.0001), luminal B/HER2-negative (aHR = 0.06, p = 0.0093; and, 0.46, p = 0.028), and luminal B/HER2-positive (aHR = 0.14, p = 0.01; and, 0.38, p < 0.0001) breast cancers. Notably, OS benefits were found in patients with luminal A (aHR = 0.62, p = 0.002), luminal B/HER2-negative (aHR = 0.30, p < 0.0001), basal-like (aHR = 0.40, p < 0.0001), and HER2-enriched (aHR = 0.50, p = 0.03), but not luminal B/HER2-positive diseases. Remarkably, when considering DM, luminal A patients who received RT demonstrated a lower cumulative incidence of DM than those without RT (p = 0.02).

CONCLUSION

In patients with luminal A breast cancer who undergo BCS, RT could decrease the likelihood of tumor metastasis. After RT, the tumor's hormone receptor status may predict tumor control regarding LR, RR, and DFS. Besides, the HER2 status of luminal breast cancer patients may serve as an additional predictor of OS after post-BCS RT. However, further prospective studies are required to validate these findings.

The effect of adjuvant radiotherapy after breast-conserving surgery in elderly women with T1-2N0 estrogen receptor-negative breast cancer

PURPOSE

To evaluate whether adjuvant radiotherapy (RT) following breast-conserving surgery (BCS) results in better survival among women ≥ 70 years with T1-2N0 estrogen receptor (ER)-negative breast cancer.

METHODS

In this retrospective cohort study, we included patients who met the inclusion criteria between 2010 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) program. Univariate and Multivariate Cox proportional analysis were used to identify the risk factors for overall survival (OS) and breast cancer-specific survival (BCSS). Kaplan-Meier survival analysis was used to compare the prognosis of patients with or without adjuvant RT. Propensity score matching (PSM) was applied to perform a 1:1 matched case-control analysis.

RESULTS

A total of 4201 women were included in this study, with a median follow-up time of 64 months (range: 0-107 months). Of these patients, 2811 (66.9%) received adjuvant RT, while 1390 (33.1%) did not. Patients who did not receive adjuvant RT were more likely to be aged ≥ 80 years old, have a single marital status, larger tumors, and HER2-positive status (p < 0.05). Multivariate Cox proportional analysis indicated that receiving adjuvant RT was an independent factor associated with better OS and BCSS before and after PSM (P < 0.001). The survival curves before and after PSM showed that patients achieved an improved OS and BCSS from adjuvant RT (P < 0.005). In the subgroup analysis, there was no survival benefit trend from adjuvant RT in patients who were ≥ 80 years, or those with T1mic+T1a, T1b tumors.

CONCLUSIONS

The use of RT following BCS in older women with T1-2N0 ER-negative breast cancer is associated with improve OS and BCSS. However, the potential benefit may be relatively limited for patients ≥ 80 years, or those with T1mic+T1a, T1b tumors.