Overweight women should undergo mammography screen tests more frequently than women with lower BMI, suggests a new study.

BMI or Body Mass Index is a measure of body fat based on height and weight. An overweight person has a BMI of 25 or more, while a BMI of 30 or higher is considered obese.The research, presented at the annual meeting of Radiological Society of North America 2017, stated that women with higher BMI face an increased risk of not detecting the breast tumour until it has become large."When a clinician presents the pros and cons of breast cancer screening to the patient, having high BMI should be an important 'pro' argument," said Fredrik Strand, a researcher at the Karolinska University in Stockholm, Sweden.

"In addition, our findings suggest that women with high BMI should consider shorter time intervals between screenings."The researchers studied 2,012 cases of breast cancer and looked for how disease progression was related to BMI and breast density. Researchers identified the risk factors associated with tumours that do not get detected until larger than two centimetre, or about the size of a peanut.The two cm size is important because it is one of the parameters used to separate stage I and stage II cancers.In addition, tumour size is known to be strongly associated with prognosis, a medical term used for predicting the likelihood of a person's survival.

The results found that both the BMI and the breast density were associated with having a large tumour at diagnosis. However, for interval cancers, or cancers detected within two years of a normal mammogram, only BMI was linked with having a large tumour.Also, women with higher BMI had worse prognosis than women with lower BMI among interval cancers.