Adverse events connected to breast cancer treatment and their associated decrease in quality of life scores.

BackgroundBreast cancer is the most commonly diagnosed form of cancer in the UK, with over 55,000 newly diagnosed cases annually. Fortunately, many patients are cured, with a five-year survival rate of about 80%. Adjuvant chemotherapy in early breast cancer is common and has been shown to increase survival but frequently comes with several adverse events. These can impact patients quality of life (QoL) and influence health care costs. Relatively little is known about the magnitude of effects on the QoL of specific toxicities and toxicity profiles. MethodsAdverse event and QoL data (using EQ-VAS and EQ5D) from sub-studies embedded in two different randomized controlled trials (RCTs) of standard adjuvant chemotherapy regimens were used in the analysis. Adverse events were grouped into 20 main toxicity categories. QoL data were reported at baseline and following phases of chemotherapy treatment. Correlations between toxicity groups were explored. Univariate and multivariate analyses investigated the association between individual adverse events and reported QoL. To predict the impact of specific adverse events, a regression model specification was developed based on data from one trial using a backwards selection procedure and assessed for validity using data from the other trial. ResultsThe most frequently reported toxicities in both trials were Alopecia, Lethargy-Depression-Anxiety, Nausea-Vomiting and Stomatitis. The univariate analysis showed a clear decrease in patients QoL measured through the visual analogue scale (EQ-VAS). Results based on EQ5D measurements did not show a clear direction of toxicities influence on patients QoL. Multivariate results demonstrated a significant change in QoL for Lethargy-Depression-Anxiety, Diarrhoea, Skin-disorders, Infection, Dyspnoea-Respiratory and specified pain. ConclusionsOnly a small part of the change in patients QoL is induced by the different adverse events the patients faced. Results based on VAS showed a much bigger influence of certain adverse events on patients QoL than those derived from EQ5D, leading to the question of whether EQ5Ds domains are capturing what is of importance to patients during chemotherapy treatment.