For pre-menopausal women, it is notoriously unreliable. We should not depend on mammography. However, there is no evidence that today's low level radiation mammography causes cancer as some of us had heard. There are credible people who do not believe that BSE saves lives. Early diagnosis is not necessarily better - it just may be.
Cancer can find other routes other than the lymph system.
A good practitioner can be asked to examine a woman's breasts as often as she needs the reassurance. This guilt lets people off the hook by allowing them to blame women for their ill health. There are still no clear preventative measures for breast cancer as there are for other cancers. Women who phone Willow often feel guilty about their cancer. After that, I couldn't imagine this woman not telling me the truth.