Mortality After Invasive Second Breast Cancers Following Prior Radiotherapy for DCIS

Abstract

Background: Women with a history of ductal carcinoma in situ (DCIS) are at increased risk for developing a second breast cancer (SBC). A prior meta-analysis of randomized studies of radiotherapy (RT) for DCIS has shown a trend toward increased breast cancer–specific mortality after SBC, but it did not have the power needed to detect a significant difference, due to a limited number of recurrences. This study sought to evaluate the impact of RT for DCIS on mortality after SBC in a larger cohort. Patients and Methods: Using the SEER database, 3,407 patients were identified who received breast-conserving therapy with or without RT for primary DCIS in 2000 through 2013 and subsequently developed a stage I–III invasive SBC within the same time period. Fine-Gray competing risk models were used to study the association between receipt of RT and mortality after SBC. Results: Prior RT was found to be associated with higher rates of breast cancer–specific mortality (hazard ratio [HR], 1.70; 95% CI, 1.18–2.45; P=.005), even after controlling for cancer stage. Interaction analysis suggested that this risk trended higher in patients with ipsilateral versus contralateral SBC (HR, 2.07 vs 1.26; P=.16). Furthermore, compared with patients who developed contralateral SBC, those with ipsilateral SBC were younger (P<.001) and more often lacked estrogen receptor expression (P<.001). Conclusions: Patients who previously received RT for DCIS had higher mortality after developing an invasive SBC than those who did not receive RT. This finding may have implications for initial treatment decisions in the management of DCIS.

Racial and Ethnic Disparities in Rates of Invasive Second Breast Cancer Among Women With Ductal Carcinoma In Situ in Hawaiʻi

“…We found that women younger than 50 years of age had greater odds of developing iiSBC compared with women 50 years of age or older. This association is consistent with a previous study that found that not only were younger women at an increased risk of developing iiSBCs but also had an associated increased mortality rate and more biologically aggressive tumor characteristics . Younger women are typically healthier, with fewer comorbid conditions, and have longer life expectancies agnostic to their cancer diagnosis and thus reasonably have more life span to develop SBC.…”

“…This association is consistent with a previous study that found that not only were younger women at an increased risk of developing iiSBCs but also had an associated increased mortality rate and more biologically aggressive tumor characteristics. 32 Younger women are typically healthier, with fewer comorbid conditions, and have longer life expectancies agnostic to their cancer diagnosis and thus reasonably have more life span to develop SBC. This is critical given that younger women with breast cancer have an associated 12-fold increased risk of death compared with the general population.…”

Letter to the Editor: Re: “Mortality After Invasive Second Breast Cancers Following Prior Radiotherapy for DCIS”

“…The recent article by Li et al 1 reports that patients who previously received radiotherapy (RT) for DCIS had higher mortality after developing an invasive second breast cancer (SBC) than those who did not receive RT. This analysis, based on analysis of the SEER database, included 3,407 patients who received breast-conserving surgery (BCS) 6 RT for primary ductal carcinoma in situ (DCIS) in 2000 through 2013 and subsequently developed a stage I-III invasive SBC within the same period.…”