Journal of Clinical Oncology Reading Notes

The decision to use chemotherapy in addition to hormonal therapy in the treatment of axillary node-negative and estrogen receptor (ER) positive breast cancer should be based not only on baseline risk, but also on prediction of degree of benefit from chemotherapy.

A number of biologic and clinical clues have suggested that not all patients derive the same degree of benefit from chemotherapy. An overview of randomized trials suggests that younger women may benefit more from chemotherapy.

A 21-gene assay has been developed that includes genes involved in tumor cell proliferation and hormonal response, characteristics that have been reported to be associated with chemotherapy response in general.

The recurrence score is calculated on a scale from 0-100 and is derived from the reference-normalized expression measurements for the 16 cancer-related genes (Ki67, STK15, Survivin or BIRC5, CCNB1 of cyclin B1, MYBL2, GRB7, HER2, ER, PGR, BCL2, SCUBE2, MMP11 or stromelysin, CTSL or cathepsin L2, GSTM1, CD68, and BAG1, and the five reference genes.

Patients with node-negative , ER-positive breast cancer in the NSABP B20 study did not benefit equally from chemotherapy. Patients with tumors who had high RS (greater than 31) experienced a large chemotherapy benefit. Patients with tumors that had low RSs derived minimal, if any, benefit from chemotherapy treatment.

For many women with high RSs, the anticipated benefit of adding chemotherapy appears to be very favorable when compared with the risks.

Oncotype DX: Reading Notes

Oncotype DX is a diagnostic test that helps identify which women with early-stage, lymph node negative and estrogen receptor-positive breast cancer are more likely to benefit from adding chemotherapy to their hormonal treatment.
The Oncotype DX test measures the activity of different genes in a woman's breast tissue tumor tissue.

Women with lower (RS) recurrence scores have a lower risk that their cancer will return. These women also have a cancer that is less likely to benefit from chemotherapy. A lower recurrence score does not necessarily mean that there is no chance that the breast cancer will return.

Women with a higher (RS) recurrence score have a stronger chance that their breast cancer will return, but may also benefit largely from chemotherapy. A higher recurrence score does not mean that a woman's breast cancer will definitely return.