Night‐time work predisposes to non‐Hodgkin lymphoma

Abstract

Our aim was to find out whether non-Hodgkin lymphoma (NHL) was more common than expected among night-time shift workers. The Finnish job-exposure matrix (FINJEM) provided estimates of the proportion of exposed persons and the mean level of exposure among the exposed in each occupation. The probability of nighttime work in each occupation was assessed, the observed and expected numbers of cancer cases in a cohort of persons born in 1906-1945 during the years of 1971-1995 were calculated, and the cumulative index of night-time work was scored. The cohort compromised of 1,669,272 persons of whom 6,307 (3,813 men and 2,494 women) had NHL during the follow-up. Night-time work increased significantly (p 5 0.01) the risk of NHL in men, the overall relative risk being 1.10 (95% confidence interval of 1.03-1.19). Using the lag period of 10 years, the risk ratio was 1.28 (1.03-1.59) for men who worked in night-time shifts to a high degree as compared with those who had not been exposed to night-time work. Night-time workers are cancer prone and have a greater risk of NHL than population on average.

Immunometabolism: Is it under the eye of the clock?

“…Various cancers have been linked to disrupted circadian cycles, such as lymphatic [47], prostate [48,49] and breast cancer [50]. In 2007 the International Agency for Research on Cancer (IARC) claimed that shift work with circadian disruption is a highly probable human carcinogen [51].…”

Shift work and cancer – considerations on rationale, mechanisms, and epidemiology

“…Also the cut-off point used for comparing the different groups of shift workers was mainly based on the subsample numerical content. The longest exposure assessed in the different studies ranged >3.1 years (8), to >4.6 years (9), >10 years (129), ≥20 years (14,16,(19)(20)(21)130), and ≥30 years (11,12,18).…”

“…Evening work ranged from 36-58% and night work from 18-24% on average. In general, 21.9% of men and 10.7% of women work on shifts that include night work. Seven percent (7%) of shift workers work permanently at night (2).…”

“…The epidemiologic evidence of a relationship between shift work and breast cancer among women is based on nine studies (8)(9)(10)(11)(12)(13)(14)(15)(16), six of which suggest a moderately increased risk of developing breast cancer after prolonged exposure to shift work. More limited observations are available in other studies, some of which posed a warning also for cancers of the prostate (15,17,18) and colon-rectum (8,15,19), endometrium cancers (20), and non-Hodgkin's lymphoma (21) (see table 1). …”

Breast cancer among shift workers: results of the WOLF longitudinal cohort study

“…The IARC review further stated that the association between shift work and breast cancer was supported by sufficient evidence among experimental animals but only limited evidence in epidemiological studies on humans. Regarding cancer, shift work has been associated with breast cancer (5,6,7), prostate cancer (8), endometrial cancer (9), colorectal cancer (10), and Non-Hodgkin's lymphoma (11). The most extensively studied cancer in this context is female breast cancer.…”