Dosimetric Inhomogeneity Predicts for Long-Term Breast Pain After Breast-Conserving Therapy.

Purpose: The objective of this cross-sectional study was to characterize long-term breast pain in patients undergoing breast-conserving surgery and radiation (BCT) and to identify predictors of this pain.

Methods And Materials: We identified 355 eligible patients with Tis-T2N0M0 breast cancer who underwent BCT in 2007 to 2011, without recurrent disease. A questionnaire derived from the Late Effects Normal Tissue Task Force (LENT) Subjective, Objective, Management, Analytic (SOMA) scale was mailed with 7 items detailing the severity, frequency, duration, and impact of ipsilateral breast pain over the previous 2 weeks. A logistic regression model identified predictors of long-term breast pain based on questionnaire responses and patient, disease, and treatment characteristics.

Results: The questionnaire response rate was 80% (n=285). One hundred thirty-five patients (47%) reported pain in the treated breast, with 19 (14%) having pain constantly or at least daily; 15 (11%) had intense pain. The pain interfered with daily activities in 11 patients (8%). Six patients (4%) took analgesics for breast pain. Fourteen (10%) thought that the pain affected their quality of life. On univariable analysis, volume of breast tissue treated to ≥105% of the prescribed dose (odds ratio [OR] 1.001 per cc, 95% confidence interval [CI] 1.000-1.002; P=.045), volume treated to ≥110% (OR 1.009 per cc, 95% CI 1.002-1.016; P=.012), hormone therapy use (OR 1.95, 95% CI 1.12-3.39; P=.02), and other sites of pain (OR 1.79, 95% CI 1.05-3.07; P=.03) predicted for long-term breast pain. On multivariable analysis, volume ≥110% (OR 1.01 per cc, 95% CI 1.003-1.017; P=.007), shorter time since treatment (OR 0.98 per month, 95% CI 0.96-0.998; P=.03), and hormone therapy (OR 1.84, 95% CI 1.05-3.25; P=.03) were independent predictors of pain.

Conclusion: Long-term breast pain was common after BCT. Although nearly half of patients had pain, most considered it tolerable. Dosimetric inhomogeneity independently predicted for pain and should be minimized to the greatest extent possible.