Night shift work and chronic lymphocytic leukemia in the MCC‐Spain case–control study

Abstract

Chronic lymphocytic leukemia (CLL) has few known modifiable risk factors. Recently, circadian disruption has been proposed as a potential contributor to lymphoid neoplasms' etiology. Serum melatonin levels have been found to be significantly lower in CLL subjects compared with healthy controls, and also, CLL prognosis has been related to alterations in the circadian molecular signaling. We performed the first investigation of an association between night shift work and CLL in 321 incident CLL cases and 1728 population-based controls in five areas of Spain. Participants were interviewed face-to-face by trained interviewers to collect information on sociodemographic factors, familial, medical and occupational history, including work shifts and other lifestyle factors. We used logistic regression models adjusted for potential confounders to estimate odds ratios (OR) and 95% confidence intervals (CI). Seventy-nine cases (25%) and 339 controls (20%) had performed night work. Overall, working in night shifts was not associated with CLL (OR = 1.06; 95% CI = 0.78-1.45, compared with day work). However, long-term night shift (>20 years) was positively associated with CLL (OR(tertile 3 vs . day-work) = 1.77; 95% = 1.14-2.74), although no linear trend was observed (P trend = 0.18). This association was observed among those with rotating (OR(tertile 3 vs . day-work) = 2.29; 95% CI = 1.33-3.92; P trend = 0.07), but not permanent night shifts (OR(tertile 3 vs . day-work) = 1.16; 95% CI = 0.60-2.25; P trend = 0.86). The association between CLL and long-term rotating night shift warrants further investigation.

Longitude Position in a Time Zone and Cancer Risk—Response

“…Second, we disagree with Dr. Grant's assertion that the findings are random with respect to individual cancers. For example, risks associated with female breast (3), prostate (4), uterine corpus (5), and chronic lymphocytic leukemia (CLL) (6) are consistent with the previous literature that reported elevated risk in shift workers.…”

Melatonin: does it have utility in the treatment of haematological neoplasms?

“…Disruption of the circadian clockwork is one of the factors that predispose individuals to haematological neoplasms. Moreover, nocturnal work (night shifts) might disturb the normal secretion of melatonin and elevate the risk of myeloid tumours and lymphoma (Lahti et al, 2008;Yong et al, 2014;Costas et al, 2016). Further research suggests that night shift work might elevate cancer risk by suppressing melatonin secretion (Stevens and Davis, 1996;Reiter et al, 2006).…”

Association of shiftwork and immune cells among police officers from the Buffalo Cardio-Metabolic Occupational Police Stress study

“…Disruption in rhythms of white blood cells (WBCs) or elevated levels have been associated with several chronic conditions including type 2 diabetes mellitus (T2DM), coronary artery disease, stroke, and leukemia, just to name a few (Costas et al, 2016; Danesh et al, 1998; Ford, 2002; Libby et al, 2016; Vozarova et al, 2002). Recent reviews discuss the wide array of immune components and functions controlled by or, at least, influenced by circadian rhythms.…”