Our study reports a trend associating obesity with decreased rates of MMR deficiency (mean BMI 36.5 for MMR proficient tumours compared to 31.5 for MMR deficient, p = 0.066), and although this trend is not significant, this association has been reported in both colorectal and endometrial cancer studies [42,44]. This evidence concerns the gene MRC1 and obesity due to melanocortin 4 receptor deficiency.