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

Background Breast 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. Methods Adverse 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. Results The 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. Conclusions Only 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 EQ5D’s domains are capturing what is of importance to patients during chemotherapy treatment. ### Competing Interest Statement The authors have declared no competing interest. ### Clinical Trial ISRCTN 68068041 ### Funding Statement The TACT and TACT2 study were funded by Cancer Research UK. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The TACT2 study was approved by the Scotland Multi-Research Ethics Committee (MREC 04/MRE00/88) and local research and development offices. TACT (CRUK01/001) was approved by the national South East Multi-Research Ethics Committee (MREC 00/1/59) and the local ethics committees of all participating centres. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes Data are not available for sharing.