The expression of the P16 protein, which inhibits cell growth, may be a useful biomarker for predicting how osteosarcoma will respond to standard chemotherapy, researchers concluded after finding that P16 expression significantly correlates with chemotherapy response among patients with that form of cancer.
As a team led by Dariusz Borys of the University of California–Davis Department of Pathology and Laboratory Medicine in Sacramento explained in Human Pathology, pathologic response to neoadjuvant chemotherapy is highly correlated with survival among persons with osteosarcoma, the most common bone cancer in children. (Osteosarcoma can also affect people after age 60 years.) However, there are no established molecular markers to predict response to this treatment.
The research group analyzed data from pretreatment biopsy specimens of 40 patients with osteosarcoma. The median age of the patients was 15 years (range, 9 to 75 years), and 35% of the biopsied tumors were located in the femur. P16 expression was found to be present in 62% of the specimens.
Following chemotherapy, during surgery to remove the tumor, specimens were again collected and analyzed. Median tumor necrosis was 90%, and 55% of patients experienced “good” chemotherapy response, defined as tumor necrosis of at least 90%. These patients were significantly more likely to have had tumors that expressed the P16 protein.
After the researchers controlled for patient age and gender and for tumor subtype and location, P16 expression was independently associated with chemotherapy response.