Abstract
Although radiation-induced cardiotoxicity has been addressed, its prognostic relevance to modern radiotherapy (RT) techniques is unclear. This study assessed the impact of adjuvant RT on heart-related deaths in patients with ductal carcinoma in situ. Patients who underwent adjuvant RT after breast-conserving surgery between 1988 and 2008 were identified from the Surveillance, Epidemiology, and End Results database. Kaplan‒Meier and competing risks analyses were conducted after propensity score-matching according to tumor laterality. A total of 41,526 propensity-matched patients were identified (n = 20,763 for either left- or right-sided tumor). In the analysis of the cumulative incidence of heart-related mortality events, there was a greater risk increment in the left-sided group over the first to second decades after RT in patients aged ≤ 50 years (P = 0.048). Competing risks analysis of the young patients showed that left-sided RT was associated with higher heart-related mortality rates (Grey’s test, P = 0.049). The statistical significance remained after adjusting for other covariates (subdistribution hazard ratio 2.35; 95% confidence interval 1.09‒5.10). Regarding the intrinsic effect of modern RT techniques, further strategies to reduce heart-related risks are needed for young patients. Close surveillance within an earlier follow-up period should be considered for these patients in clinics.
Highlights
Radiation-induced cardiotoxicity has been addressed, its prognostic relevance to modern radiotherapy (RT) techniques is unclear
We evaluated the cardiac mortality inherently induced by postoperative adjuvant RT in patients with ductal carcinoma in situ (DCIS) who underwent left- or right-sided breast irradiation following breast-conserving surgery
The cumulative incidence of patients aged ≤ 50 years showed that left-sided RT was associated with a higher incidence rate of heart-related death and suggested the potential risk in the first to second decades following RT
Summary
Radiation-induced cardiotoxicity has been addressed, its prognostic relevance to modern radiotherapy (RT) techniques is unclear. Regarding the intrinsic effect of modern RT techniques, further strategies to reduce heart-related risks are needed for young patients. Over the past few decades, the cardiotoxicity following the ipsilateral breast radiotherapy (RT) has been discussed[1,2,3] It is still unclear on whether modern breast RT techniques still induce clinically significant cardiac-specific risks. Regarding the cardiotoxic effects of major chemotherapeutic agents in breast cancer[4,5], heart-related risks originating solely from the radiation in diverse clinical settings are not evaluated. We evaluated the cardiac mortality inherently induced by postoperative adjuvant RT in patients with ductal carcinoma in situ (DCIS) who underwent left- or right-sided breast irradiation following breast-conserving surgery. Variables Laterality Left Right Age (years) ≤ 50 51–70 > 70 Race Caucasian African–American Others Unknown Marital status Married Not married Unknown Year of diagnosis 1988–1993 1994–1998 1999–2003 2004–2008 Geographic region Pacific coast East Northern plains Southwest Alaska
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