Recent clinical trials on cancer immunotherapy drugs have demonstrated improved breast cancer patient outcomes. Pembrolizumab, a cancer immunotherapy checkpoint inhibitor, has been utilized in clinical breast cancer trials due to its reasonable safety profile. Pembrolizumab acts on cancer cells by blocking programmed death-ligand-1 (PD-L1), allowing our adaptive immune system to function as it normally would. PD-L1 is a cell surface protein that induces T cell apoptosis upon binding to PD-1 receptors on T cells, a key mechanism for immune evasion. Through measuring overall response rate (ORR) and pathological complete response (pCR), researchers have measured the efficacy of Pembrolizumab. While it was generally found that there was no statistically significant difference for ORR, the data collected for pCR shows a statistically significant difference in patients who received pembrolizumab treatment compared to those who received the control. This data offers promising results that pembrolizumab could potentially improve breast cancer patient survival outcomes.

Breast density measures the amount of fibrous and glandular tissue in the breast compared to fat tissue. Dense breasts, which have higher amounts of fibrous and glandular tissue and lower amounts of fat tissue, make it harder to detect breast cancer in mammograms. Additionally, dense breast tissue increases the risk of developing breast cancer. This literature review evaluates the possible benefits of notifying women about their breast density based on the relationship between breast density and breast cancer.