Does the toxicity of endocrine therapy persist into long-term survivorship?: Patient-reported outcome results from a follow-up study beyond a 10-year-survival

BACKGROUND: Endocrine treatment (ET) is a highly effective breast cancer treatment but can distinctly impair breast cancer patients’ quality of life (QOL). In a patient-reported outcome (PROs) study conducted by the authors in 2011, patients reported higher ET-induced symptom levels than known from the registration trials, and was underestimated. Based on these study results, we investigated the long-term sequelae of ET reported by breast cancer survivors (BCS) in a follow-up study conducted 5–10 years after an earlier assessment. METHODS: BCS who had participated in the earlier study (n = 436) were approached for study participation either at one of their routine follow-up appointments or via mail; consenting patients were asked to completed the same PRO assessment used in the original study (FACT-B + ES). BCS with relapse/ progressive disease were excluded from the analysis. We compared long-term endocrine symptomatology and overall QOL outcome (i.e. FACT-G and -ES sum score). RESULTS: A final sample of 268 BCS was included in the analysis. BCS reported a significant improvement of the overall endocrine symptomatology (baseline mean = 59 vs. follow-up mean = 62, p < 0.001), physical (baseline = 23.9 mean vs. follow-up mean = 24.8, p < 0.01) and functional well-being (baseline mean = 21.7 vs. follow-up mean = 22.7, p = 0.013) and overall QOL (mean baseline = 88.3 vs. mean follow-up = 90.9, p = 0.011). However, the prevalence of particular symptoms, well-known to be ET induced, did not change over time such as joint pain (baseline = 45.5% vs. 44.2%, n.s. difference), lack of energy (36.4% vs 33.8%, n.s. difference), weight gain (36.8% vs. 33.9%, n.s. difference) or vaginal dryness (30.2% vs. 33%, n.s. difference) and the proportion reporting lack of interest in sex increased (40.4% vs. 48.7%, p < 0.05). CONCLUSION: Presented results indicate that BCS recover well in terms of overall endocrine symptomatology and quality of life but experience some clinically relevant and unfavorable ET-related long-term effects.