This study investigated what could be missing in tools that predict patient outcome from breast cancer. The current tools do not explain differences in outcomes that are being found in research. 

Previous studies have shown that patients with breast cancers found by mammogram screening have a higher chance of survival than those with cancers found due to symptoms, but the tools can not completely explain why this is.

The current study shows that HER-2 positive cancers (HER2 is a protein which promotes growth of cancer cells) are less common when the cancer is found through screening. These types of cancers have previously been shown to achieve worse outcomes. Yet, this is not included in prediction tools, and neither is the method of finding the tumour.

Not including these factors in current outcome prediction tools may give an overly negative view of the potential outcome for women with screen-detected cancers. In addition, as the tools are used when deciding on treatment, some cancers may get over-treated.

The prediction tools should be made more accurate by including HER-2 status of the tumour and how the tumour was found.