How obesity causes cancer, and may make screening and treatment harder

Focusing on just two types of cancer, breast cancer in women and prostate cancer in men, some evidence suggests that obesity can delay the identification of cancer through screening – but does not reduce the importance or accuracy of screening tools or programs. For breast cancer, the most common form of cancer in women in Australia, the good news is that screening accuracy is similar across weight status. The Swiss national health survey found the accuracy of mammography is maintained in obese women – with similar ability of the tests to detect cancers, but reduced ability to ensure the positive result definitely means cancer. This meant obese women had a 20% higher false positive rate than normal weight individuals, but does not suggest any cancers were missed. The troubling news though is, studies suggest obese women with breast cancer detected through mammogram tend to present to their doctors later, and when the cancer is more serious, than their healthy weight counterparts. The exact reasons for this are not clear but may include possible difficulties in breast self-examination and delayed health-seeking. Such findings reinforce the crucial importance of strategies to encourage appropriate cancer screening and timely medical follow-up among overweight and obese women. The Conversation, 20/03/17