Associations of pretreatment emotional distress with adherence to therapy for patients with locally advanced rectal cancer: a post hoc analysis of the Chinese FOWARC phase 3 randomized clinical trial

Background: Non-adherence in advanced rectal cancer therapy is common and severely impairs clinical outcomes. Although behavioral research suggests emotional factors influence adherence, limited evidence links pretreatment emotional distress (PED) to treatment adherence in rectal cancer patients. Methods: This post hoc analysis of a phase 3 randomized clinical trial was conducted from June 9, 2010, to February 15, 2015, involving 219 patients (assigned to receive neoadjuvant therapy with fluorouracil plus radiotherapy [group A, 67 patients], modified fluorouracil, leucovorin, and oxaliplatin [mFOLFOX6] plus radiotherapy [group B, 66 patients], or mFOLFOX6 alone [group C, 86 patients] followed by TME resection and postoperative adjuvant chemotherapy) with locally advanced rectal cancer from the main center. The PED of patients was measured through the emotional dimension items in the Quality of Life Questionnaire-Core Questionnaire (QLQ-C30). The primary outcome was adherence to therapy, with non-adherence defined as patients in groups A and B receiving fewer than ten cycles of chemotherapy or less than 37 Gy of radiotherapy, and patients in group C receiving fewer than ten cycles of chemotherapy. Multivariable logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) for adherence by PED levels. Additionally, the structural equation model (SEM) was utilized to analyze the impact pathways of PED on adherence. Results: Among the 219 patients (142 men; mean age, 53.4 years) who completed the QLQ-C30 scale, 27.8% (61/219) demonstrated non-adherence to the treatment regimen. Multivariable analyses showed that each 1-point increase in PED score raised non-adherence risk by 4.37 times (OR: 4.37, 95% CI: 1.92-9.96, P < 0.001). The SEM analysis revealed that PED score was positively correlated with the risk of non-adherence (standardized regression coefficients [beta] = 0.25, 95% CI: 0.11 to 0.28), while economic burden was positively correlated with PED (beta = 0.17, 95% CI: 0.11 to 0.28), and could indirectly affect adherence through PED (beta = 0.04, 95% CI: 0.01 to 0.09). Conclusions: Higher levels of pretreatment emotional distress were associated with an increased risk of treatment non-adherence, thereby highlighting the potential significance of addressing emotional distress in cancer management.