Correlation between breast cancer and lifestyle within the Gulf Cooperation Council countries: A systematic review

Table 4 Paper results from case-control trials exploring the association of obesity and breast cancer

Ref.	Sample size and characteristics	Cases		Controls		Association between BC and obesity	Other findings
		Age (mean ± SD)	Anthropometric Measurements	Age (mean ± SD)	Anthropometric measurements
[40]	348 Saudi women (58 newly diagnosed with BC and 290 controls)	48.5 ± 7.1	BMI > 30: 71.4%	49.2 ± 6.9	BMI > 30: 70.7%	There was no significant association between BMI and BC	BC was significantly correlated with age at marriage and age at menopause; There was no significant correlation between PA and BC; 62.1% of cases were pre-menopausal and 44.8% were post-menopausal
[41]	500 women (250 newly diagnosed with BC, 250 no previous history of any cancer) from 2 hospitals in Riyadh, KSA	45.7 ± 7.8	Mean (± SD): 31.2 (± 7.0)	43.9 ± 7.5	Mean ± SD 30.7 ± 7.6	No significant difference between the BMI of the cases and controls	There was a slight significance (P = 0.011) between the age of the 2 groups; Women with BC entered menopause significantly younger than the controls (P = 0.022); Mean (± SD) of menopause was 46.6 (± 6.4) for the controls and 48.7 (± 5.2) which was significant (P = 0.022)
[61]	997 women from 1 research centre in Riyadh, KSA. 499 newly diagnosed and confirmed BC and 498 age-matched controls	44.8 ± 11.5	Mean (± SD); 29.5 (± 6.2)	36.8 ± 12.8	Mean ± SD 29.4 ± 6.2	There was no significant difference between the BMI of the cases and controls	BC patients were significantly older than controls (P = 0.0001); A positive association between the highest quartile triglyceride level and BC risk (OR = 2.90); Mean ± SD menopausal age for cases was 48.2 ± 7.6 yr and 47.9 ± 8.1 yr for the controls
[39]	1172 women aged 18+, 534 histologically confirmed primary BC cases and 638 unmatched controls that were BC free	43.6 ± 8.3; 15% ≤ 35 yr, 85% > 35 yr	29.4% overweight and 46.4% obese	Mean not provided; 31.5% ≤ 35 yr, 68.5% > 35 yr	30.3% overweight and 31.0% obese	Overweight/ obese BMI significantly increased the BC risk compared to normal BMI (OR = 2.29). It is an independent risk factor for BC. Obesity/obese proportion was significantly high in BC group than controls (OR = 1.74 and P < 0.0001); Being overweight or obese in the pre- and postmenopausal ages were both significantly associated with increased BC risk compared to controls	Low education, unemployment and marriage were significantly associated with higher BMI (P < 0.0001); Low education was associated with an increased risk of BC (P < 0.0001); 49.7% of cases were premenopausal and 50.3% were postmenopausal. Post-menopausal women were found to have a positive association with BC risk

BMI > 24.9 is overweight and BMI-30 is obese. BMI: Body mass index; PA: Physical activity; SD: Standard deviation; BC: Breast cancer; OR: Odds ratio; CRP: C-reactive protein; TNF-α: Tumour necrosis factor- alpha; KSA: Kingdom of Saudi Arabia.