Introduction/framework/objectives:

There are work circumstances that can increase the oncological risk and Breast Cancer is no exception to this situation. However, knowledge on this subject is not particularly abundant among workers and/or Occupational Health and Safety teams professionals. This review was intended to mitigate this issue.

Methodology:

This is a Bibliographic Review, initiated through a search carried out in January 2022 in the databases: “CINALH plus with full text, Medline with full text, Database of Abstracts of Reviews of Effects, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Cochrane Methodology Register, Nursing and Allied Health Collection: comprehensive, MedicLatina and RCAAP”.

Content:

Night shifts are chronodisruptive, probably due to decreased melatonin production. Other researchers add that night work and/or nocturnal exposure to light disturbs the circadian rhythm and hormone secretion (with emphasis also on prolactin, glucocorticoids, adrenocorticotropic hormone, corticoliberin and serotonin). However, there is no consensus that night shifts imply lower levels of prolactin secretion and that this is associated with Breast Cancer. Some studies may be biased due to having studied night shifts versus exposure to light during these shifts (the latter being the situation that presents evidence of moderately increasing the risk of this Cancer). In addition, more recent investigations consider more possibly biasing variables. It is believed that nocturnal exposure to light implies changes in the production of melatonin and vitamin D. However, others consider that these data are not supported by robust scientific evidence or free of controversy, even due to the difference between the different types of night shifts. In 2007, the IARC published some data on this possible relationship- namely that night shifts were probably carcinogenic to humans (group 2A), and/or that there was evidence of an association between oncological processes and night shifts, probably for Breast Cancer in particular, based on sufficient evidence in animals and limited evidence in humans.

Discussion and Conclusions:

Most of the bibliography on the subject emphasizes night shifts and/or exposure to light during them as a work etiology, although without full consensus between causality and/or pathophysiology. Pesticides, solvents and products included in kitchen fumes (polycyclic aromatic hydrocarbons, aldehydes and polycyclic aromatic amines) are also mentioned.

It would be an asset for some Occupational Health and Safety professionals, with adequate logistical capacity, to investigate the area, subsequently disclosing the conclusions covered.

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