Chemotherapy reduces long-term quality of life in recurrence-free colon cancer survivors (LaTE study)—a nationwide inverse probability of treatment-weighted registry-based cohort study and survey

Abstract Aim Stage III colon cancer is routinely treated with adjuvant chemotherapy, which causes significant short‐term morbidity. Its effect on long‐term quality of life (QoL) is poorly investigated. The aim of this study was to investigate long‐term QoL after curative treatment for colon cancer and explore the impact of chemotherapy on general and disease‐specific QoL. Method All patients aged under 75 years operated on for colon cancer between 30 September 2007 and 1 October 2019 were identified by the Cancer Registry of Norway. Exclusion criteria were distant metastasis, recurrence, dementia and rectal/rectosigmoid cancer operation. The primary outcome measure was Gastrointestinal Quality of Life Index (GIQLI). Secondary outcome measures included the Short Form Health Survey (SF‐36). To achieve balanced groups when assessing differences in outcome measures the analyses were weighted by inverse probability weights based on a multiple logistic regression model with prechosen confounders. Results A total of 8627 patients were invited and 3109 responded (36% response rate). After exclusions 3025 patients were included, of whom 1148 (38%) had received adjuvant chemotherapy and 1877 (62%) had surgery alone, with mean follow‐up of 75.5 versus 74.5 months, respectively. The GIQLI differed significantly between the groups [mean 111.0 (SD 18.4) vs. 115.6 (SD 17.8), respectively; mean difference: −4.6 (95% CI −5.9; −3.2); p