Cancer incidence, treatment, and survival in the prison population compared with the general population in England: a population-based, matched cohort study

Background The growing and ageing prison population in England makes accurate cancer data of increasing importance for prison health policies. This study aimed to compare cancer incidence, treatment, and survival between patients diagnosed in prison and the general population. Methods In this population -based, matched cohort study, we used cancer registration data from the National Cancer Registration and Analysis Service in England to identify primary invasive cancers and cervical cancers in situ diagnosed in adults (aged >= 18 years) in the prison and general populations between Jan 1, 1998, and Dec 31, 2017. Ministry of Justice and Office for National Statistics population data for England were used to calculate agestandardised incidence rates (ASIR) per year and age -standardised incidence rate ratios (ASIRR) for the 20 -year period. Patients diagnosed with primary invasive cancers (ie, excluding cervical cancers in situ) in prison between Jan 1, 2012, and Dec 31, 2017 were matched to individuals from the general population and linked to hospital and treatment datasets. Matching was done in a 1:5 ratio according to 5 -year age group, gender, diagnosis year, cancer site, and disease stage. Our primary objectives were to compare the incidence of cancer (1998-2017); the receipt of treatment with curative intent (2012-17 matched cohort), using logistic regression adjusted for matching variables (excluding cancer site) and route to diagnosis; and overall survival following cancer diagnosis (2012-17 matched cohort), using a Cox proportional hazards model adjusted for matching variables (excluding cancer site) and route to diagnosis, with stratification for the receipt of any treatment with curative intent. Findings We identified 2015 incident cancers among 1964 adults (1556 [77<middle dot>2%] men and 459 [22<middle dot>8%] women) in English prisons in the 20 -year period up to Dec 31, 2017. The ASIR for cancer for men in prison was initially lower than for men in the general population (in 1998, ASIR 119<middle dot>33 per 100 000 person -years [95% CI 48<middle dot>59-219<middle dot>16] vs 746<middle dot>97 per 100 000 person -years [742<middle dot>31-751<middle dot>66]), but increased to a similar level towards the end of the study period (in 2017, 856<middle dot>85 per 100 000 person -years [675<middle dot>12-1060<middle dot>44] vs 788<middle dot>59 per 100 000 person -years [784<middle dot>62-792<middle dot>57]). For women, the invasive cancer incidence rate was low and so ASIR was not reported for this group. Over the 20 -year period, the incidence of invasive cancer for men in prison increased (incidence rate ratio per year, 1<middle dot>05 [95% CI 1<middle dot>04-1<middle dot>06], during 1999-2017 compared with 1998). ASIRRs showed that over the 20 -year period, overall cancer incidence was lower in men in prison than in men in the general population (ASIRR 0<middle dot>76 [95% CI 0<middle dot>73 -0<middle dot>80]). The difference was not statistically significant for women (ASIRR 0<middle dot>83 [0<middle dot>68-1<middle dot>00]). Between Jan 1, 2012, and Dec 31, 2017, patients diagnosed in prison were less likely to undergo curative treatment than matched patients in the general population (274 [32<middle dot>3%] of 847 patients vs 1728 [41<middle dot>5%] of 4165; adjusted odds ratio (OR) 0<middle dot>72 [95% CI 0<middle dot>60-0<middle dot>85]). Being diagnosed in prison was associated with a significantly increased risk of death on adjustment for matching variables (347 deaths during 2021<middle dot>9 person -years in the prison cohort vs 1626 deaths during 10 944<middle dot>2 person -years in the general population; adjusted HR 1<middle dot>16 [95% CI 1<middle dot>03-1<middle dot>30]); this association was partly explained by stratification by curative treatment and further adjustment for diagnosis route (adjusted HR 1<middle dot>05 [0<middle dot>93-1<middle dot>18]). Interpretation Cancer incidence increased in people in prisons in England between 1998 and 2017, with patients in prison less likely to receive curative treatments and having lower overall survival than the general population. The association with survival was partly explained by accounting for differences in receipt of curative treatment and adjustment for diagnosis route. Improved routine cancer surveillance is needed to inform prison cancer policies and decrease inequalities for this under -researched population.