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Summary Background Pruritus is a frequent complaint in patients with cancer. However, no large study has examined pruritus as a marker of undiagnosed cancer. Objectives To examine the association between inpatient, outpatient and emergency hospital diagnoses of pruritus and subsequent cancer diagnoses. Methods In this nationwide Danish cohort study, we used medical databases to identify all patients (n = 12 813) with a diagnosis of pruritus during the period 1978–2011 and followed them until a first-time cancer diagnosis, emigration, death or 31 December 2011. We computed standardized incidence ratios (SIRs) for cancer as the observed to expected number of cancers based on national cancer incidence rates. We calculated the 1-year absolute risk of cancer, treating death as a competing risk. Results The overall SIR of cancer was 1·13 [95% confidence interval (CI) 1·07–1·20]: 1·22 (95% CI 1·13–1·33) among men and 1·05 (95% CI 0·97–1·14) among women. The SIR was 1·20 (95% CI 1·08–1·33) among patients with a previous diagnosis of dermatological disease and 1·10 (95% CI 1·02–1·18) among patients without such a diagnosis. Both haematological and various solid cancers were observed at increased rates. Overall, the highest SIRs were observed during the first 3 months of follow-up, declining rapidly thereafter. The 1-year absolute risk of a cancer diagnosis was 1·63% and 155 patients with pruritus would have needed to be examined to detect one excess cancer. Conclusions Pruritus may be a marker of occult cancer. Further studies are needed to assess the prognostic benefit of screening for cancer in patients with pruritus.

Summary Background Earlier studies reported an increased cancer risk among patients with systemic sclerosis. Study size limitations and paucity of population-based study designs may have resulted in imprecise risk estimates. Objectives To assess cancer risk among patients with systemic sclerosis in a nationwide follow-up study. Methods Patients with a first diagnosis of systemic sclerosis from 1977 to 2006 were identified from the nationwide Danish National Registry of Patients (DNRP), whose records encompass all hospitalizations and outpatient visits. Patients’ DNRP records were linked to the Danish Cancer Registry. We compared their cancer incidence with that expected from cancer incidence in the general population, calculating standardized incidence ratios (SIRs) and 95% confidence intervals (CIs). Results Two thousand and forty patients with systemic sclerosis were identified and followed for 16 003 person-years, with a median follow-up time of 6·4 years (interquartile range 2·2–11·5). Among these patients, 222 cases of cancer were identified. The overall SIR for cancer was 1·5 (95% CI 1·3–1·7), with a gender-specific SIR of 2·2 (95% CI 1·7–2·8) for men and 1·3 (95% CI 1·1–1·6) for women. The most frequent cancers were smoking- and alcohol-related cancers including lung cancer (SIR = 1·6, 95% CI 1·2–2·0), haematological cancers (SIR = 2·5, 95% CI 1·5–4·0) and immune-related cancers (SIR = 1·4, 95% CI 1·0–1·9). Conclusions Systemic sclerosis is a risk factor for cancer, particularly smoking- and alcohol-related cancers. Men with systemic sclerosis generally are at higher cancer risk than women. Both primary and secondary cancer preventive measures are needed in the care of patients with systemic sclerosis.