A recent paper from the New England Journal demonstrates that mammographic screening paradigms have had little effect on ultimate survival. Over three decades, screening all women from the age of forty on has identified 1.1 million more early stage breast cancers but we have not seen a concommitant decrease in the number of women presenting with advanced breast cancer. This indicates that we are identifying a lot of non-aggressive, relatively benign tumors with little potential for metastatic extension. The implication is that we are overtreating millions of women with unnecessary surgery, radiation, and chemotherapy for relatively benign, clinically insignificant mammographic findings.
Of course there are those who certainly do benefit from earlier intervention, just not to the degree we previously thought (old standards proclaimed that screening mammograms reduced mortality in breast cancer by 25%). It is impossible right now to determine which women with microscopic pre-cancerous (DCIS) lesions are at higher risk for eventual transformation into aggressive, lethally invasive variants. The direction oncologic research needs to be focused on over the coming years is in the realm of genetics so, through the meticulous identification of certain proteins and genes, we can more fruitfully identify which tumors need the bazooka in the armamentarium and which can be safely observed without interventional therapy.