Risk of osteonecrosis in cancer patients

Purpose Osteonecrosis (ON) has been described in cancer patients in association with cancer and its treatment using radiotherapy or chemotherapy with and without corticosteroids; however, epidemiologic data on the overall risk of ON in cancer patients are quite limited. The purpose of this population-based cohort study was to estimate risk of ON in cancer patients. Methods A source population of 5,597,148 persons (8,998,314 person-years) aged 20 to 84 years with information recorded in the UK General Practice Research Database (GPRD) during the period January 1, 1994, to December 31, 2001, was identified as the general population cohort. From this cohort, two additional cohorts were drawn: a cohort of cancer patients (106,477 person-years) and a cohort of cancer-free patients (8,611,725 person-years). Diagnostic codes indicative or suggestive of ON were defined. All members in the two cohorts were followed-up until the earliest of the following endpoints: (i) diagnosis of ON; (ii) death; or (iii) end of the study period. Cancer treatment was not assessed. Incidence rates of ON (all sites) in the two cohorts and the age- and sex-adjusted relative risk of ON for the cancer patients were calculated. Results The estimated incidence rate of ON among the cancer cohort was 1.32 per 10,000 person-years (95% CI = 0.75–2.15). In the cancer-free population, the incidence rate was estimated to be 0.28 per 10,000 person-years (95% CI = 0.25–0.31). Compared with the risk among the cancer-free cohort, the age- and sex-adjusted relative risk for ON in cancer patients was 3.38 (95% CI = 1.95–5.84, P < 0.0005). Conclusion Compared with a cancer-free population, cancer patients are estimated to be 3.4 times more likely to develop ON. These preliminary data suggest that with increasing survival of cancer patients, health care providers and patients need to be aware of ON as a potential factor in comorbidity.