A new research study shows a direct correlation between loss of a tumor suppressor protein expression in a cancer tumor and patients’ long-term survival after chemotherapy. The research paper, entitled “Loss of the retinoblastoma tumor suppressor correlates with improved outcome in patients with lung adenocarcinoma treated with surgery and chemotherapy,” was published in Human Pathology.
Most types of human cancers present deregulation or inactivation of the retinoblastoma tumor suppressor pathway. However, the expression of a retinoblastoma tumor suppressor protein (pRB) is maintained in most cancers in a hyperphosphorylated state. Recent research data has suggested that this protein, an important regulator of cell cycles, remains active in cancer tissues, though there is ongoing research related to this protein function in tumor suppression.
In order to test if the presence and state of the protein had clinical relevance in patient treatment and outcome, scientists at the Lawson Health Research Institute analyzed tissue sections from 91 lung adenocarcinoma patients looking for a link between the protein’s absence and patient survival. All patients had undergone chemotherapy and surgical resection. The tissue samples were tested for presence and quantification of normal and hyperphosphorylated pRB. Researchers found that pRB expression was lost in 15% of the lung cancer patients. In these patients, the survival rate at five years was significantly improved, reaching 92%. In comparison, patients expressing pRB had an average survival rate of 49%.
Dr. Fred Dick, lead author of the study, commented in a press release, “These results are surprising because pRB has traditionally been understood to be a suppressor of tumor growth. This study illustrates that the absence of pRB actually results in improved outcomes for those adenocarcinoma patients who undergo chemotherapy and surgery.”
Chemotherapy is an aggressive and debilitating therapy and identification of predictors of its success represents a great step forward in personalized treatment plans. This research study presents pRB as a possible biomarker for treatment response of adenocarcinoma patients. Moreover, further research might also reveal the potential of pRB as a target for drug therapy, with the goal of making adenocarcinoma cases more sensitive to chemotherapy.