Among patients with T3N0 (stage II) colon cancer, gene expression tests such as the 12-gene recurrence score assay are used to refine prognostic stratification and aid in decision making about adjuvant chemotherapy.
The utility of gene scores for prognostication in rectal cancer patients was evaluated in a clinical trial ( Validation of the 12-gene colon cancer recurrence score as a predictor of recurrence risk in stage II and III rectal cancer patients, published by Reimers MS, Kuppen PJ, Lee M, Lopatin M, Tezcan H, Putter H, Clark-Langone K, Liefers GJ, Shak S, van de Velde CJ).
Given the small study size and lack of independent validation, we still recommend postoperative combined modality therapy for rectal cancer patients who undergo initial resection and have pathologically staged T3N0 tumors. Determination of risk using the 12-gene recurrence score may have a role in patients with margin-negative T3N0 tumors after a total mesorectal excision who wish to avoid the potential toxicity of postoperative radiotherapy (eg, women who aspire to bear children). If such patients are willing to accept uncertainty as to the ability of the test to predict the value of adjuvant therapy, surveillance without postoperative chemoradiation or chemotherapy alone is an option if they are found to be at low risk and if they did not have preoperative chemoradiotherapy.
Given the lack of data, it is recommended not use the 12-gene recurrence score to make decisions about postoperative chemotherapy in patients who have undergone neoadjuvant chemoradiotherapy.
Original Wolters Kluwer Article