Boolean operators

(Nurses OR Nurse) AND (nightshift) AND (breast cancer)

P= Nurses OR Nurse

E= Nightshift

O= Breast Cancer

Risk ratio was 62.5% (the association between breast cancer and nightshift work)

strengths

33 studies included that were assessed. Good range of data gathered

Quality assessment check completed using the Newcastle- ottawa scale. Most above 7 * indicating the studies were not biased.

Studies from different places around the world.

Used 5 databases to locate papers; CINAHL, Embase, Scopus, Web of Knowledge and Pubmed.

Used lots of keywords and boolean operators.

systematic review had to be translated from Spanish to english

weaknesses

 Unpublished studies not included

Population was not solely nurses, it also included members of the armed forces, general public, twins database and workers in other sectors.

No confidence intervals

NHS1 found little to no association of nightshfit work and breast cancer due to the older age group recruited mean that many were retired by the end of the study as only 3% remained working.

NHS2 found a strong association between breast cancer and night shift work over a long period of time 20+ years.

Hazard ratio was 1.40- 2.15

strengths

Confidence interval 95%

Prospective cohort study

Differential screening took place.

Included a table on different time scales spent working night shifts

Wide range of participants

weaknesses

Only 3% from NHS1 cohort study still worked, rest had retired.

Only females included in study.

participants could not be blinded and no indication if researchers were blinded.

3 results on TRIP

15 results on Pubmed