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

Abstract 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; 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 loss of interest in sex even deteriorated over time (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.