The association between pre-existing cardiovascular disease and cancer treatment receipt in a population-based cancer registry

Baseline cardiovascular disease (CVD) has been linked with poorer outcomes for patients with cancer. The precise mechanisms underpinning that are poorly understood but may include reduced treatment receipt. We estimated the association between pre-existing CVD and cancer treatment receipt using population-based cancer registry records. Records of all adults diagnosed with cancer (excluding non-melanoma skin cancer) in Northern Ireland in 2009–2019 were linked with comorbidity and treatment data. The adjusted odds ratios (aOR) of receiving various cancer treatments for patients with previous cardiovascular diagnoses were estimated using multivariable logistic regression, adjusting for established confounders. Subgroup analyses were conducted for combinations of 24 tumour sites, 11 cardiovascular conditions, and 5 cancer treatment modalities. Kaplan-Meier curves and Cox proportional hazards model were used to analyse time to treatment. 81,341 cancer patients were included, with a mean age of 67.1 ± 14.1 years. The most common cancers included were breast (15.8%), lung (14.1%) and colorectal cancer (13.5%). Patients with pre-existing CVD (23.4%) were 30% less likely to receive any cancer treatment than patients without (aOR = 0.70 [95%CI 0.67, 0.73]). This reduction varied between treatment modalities with 30% for chemotherapy (aOR = 0.70 [95%CI 0.67, 0.73]), 28% for radiotherapy (aOR = 0.72 [95%CI 0.66, 0.79]), and 23% for surgery (aOR = 0.77 [95%CI 0.74, 0.80]). Hormone therapy showed no significant overall difference (aOR = 1.02 [95%CI 0.94, 1.11]). At 6 months post-diagnosis, patients with pre-existing CVD had a 14% (0.14 [95%CI 0.13, 0.15]) lower probability of initiating cancer treatment compared to those without. Pre-existing CVD was associated with an overall lower odds of cancer treatment, although the magnitude of this decrement varied according to the primary tumour, treatment modality and the type of CVD. These data present granular population-based insights into the impact of cardiovascular comorbidities on receiving cancer treatment and should be accounted for when reporting survival variations and healthcare policymaking.