Given the high usage of radiation therapy (RT) for women ≥ 70 years of age with T1, estrogen receptor-positive (ER+) tumors undergoing breast-conserving therapy (BCT) despite data from randomized trials supporting omission of RT, researchers reviewed their institutional experience to determine if RT use is influenced by risk factors for local recurrence or comorbidities.
They analyzed overall, 323 patients with 327 cancers and found that only younger age; and larger tumor size were associated with RT use on multivariable analysis. They observed recurrence-free survival of 98% vs 93% with and without RT, respectively. In addition, they noted improved overall survival in those who received (92% vs 89%); although this effect was not statistically significant.
In these women, adjuvant radiation was neither influencing the factors; associated with the risk of local recurrence nor by the estimated risk of death in 10 years. Despite data from randomized trials supporting omission of radiation therapy (RT) for women ≥ 70 years of age with T1; estrogen receptor-positive (ER+) tumors undergoing breast-conserving therapy (BCT), RT usage remains high. The researchers reviewed the institutional experience to determine if risk factors for local recurrence or comorbidities influenced use.
Epidermal growth factor
Women ≥ 70 years of age with T1, ER+, human epidermal growth factor receptor 2-negative (HER2−) tumors undergoing BCT; in 2010–2012 were identifying from a prospectively maintained database. Ten-year estimated mortality was calculating using the Suemoto index. The associations of clinicopathological features; and mortality risk on receipt of RT were examined.
Overall, 323 patients with 327 cancers were identifying. Median age was 75 years; median tumor size was 1 cm, and all were clinically node negative; 53.7% of patients received RT. RT usage decreased with age (73.6%, age 70–74 years; 49.5%, age 75–79 years; 33.3%, age 80–84 years; 10.7%, ≥ 85 years; p < 0.001). Within age groups, estimated mortality did not impact RT usage.
On multivariable analysis, only younger age and larger tumor size were associating with RT use. Recurrence-free survival was 98% versus 93% with and without RT, respectively (p = 0.011). Those who received adjuvant radiation also had improved overall survival (92% vs. 89%), although this effect did not reach statistical significance (p = 0.051).
Risk of local recurrence
Neither the factors associated with risk of local recurrence nor the estimated risk of death; in 10 years were associating with use of adjuvant radiation in a large cohort of women ≥ 70 years of age; with small ER+ breast cancers treated with breast-conserving surgery.
Despite attempts to minimize morbidity, radiation therapy (RT); has remained the standard of care for patients undergoing breast-conservation therapy; based on data from the Early Breast Cancer Trialists’ Cooperative Group meta-analyses; demonstrating that the reduction in local recurrence associated with the use of RT; but is associating with an improvement in overall survival (OS). However, this difference did not become apparent until 15 years of follow-up; and was only found in women with a >10% reduction in local recurrence at 5 years.