Unmet Need in the Treatment of Colon Cancer
Addressing an Unmet Need in the Treatment of Colon Cancer
Colon cancer is the third most prevalent cancer in both men and women in the USA and is the third most common cause of cancer-related deaths. Approximately 30% of patients with colon cancer present with stage II disease.Current NCCN Guidelines do not recommend the routine use of adjuvant chemotherapy for all patients with stage II colon cancer but to advise consideration adjuvant treatment in the setting of high recurrence risk. The five-year survival rate for the overall stage II patient population has been estimated to be 75-80% following surgical resection. Despite these relatively high cure rates with surgery alone, a significant proportion of stage II member´s cancer will recur, and considerable effort has been made to identify markers of risk to distinguish those members at low risk from those at greatest risk of disease recurrence, who would be candidates for adjuvant chemotherapy. Unlike in breast cancer, where molecular markers such as ER, PR, and HER2 have been in long-standing clinical use, markers in stage II colon cancer have been limited to clinical and pathologic parameters. The presence of any of the following features places a member into a “high risk” category while a member without these features would be considered “standard risk”:
- T4 lesions
- Fewer than 12 lymph nodes examined
- Presence of bowel perforation or obstruction
- Poorly differentiated tumors,
- Lymphatic or venous invasion
These parameters are generally qualitative and are not informative for further differentiating risk in standard risk members, who constitute the majority of stage II colon cancer. The Oncotype DX Colon Cancer Assay was developed to address this need for new markers to better individualize treatment decisions for members with stage II colon cancer.
Risks of Adjuvant Chemotherapy
For each stage II patient, the potential benefit of adjuvant chemotherapy must be considered against the risk of chemotherapy-related complications. The incidences of major chemotherapy-related adverse events have been well documented. The side effects of chemotherapy can be significant not only in terms toxicity but also quality of life. The selection of members for chemotherapy is subjective and based on risk assessment using clinical/pathologic markers as well as member age, co-morbidities, member preference and ability to tolerate chemotheraphy. The NCCN Guidelines list a wide range of acceptable management strategies for resected stage II colon cancer including observation, 5FU/LV or capecitabine, 5FU/LV/oxaliplatin (for high risk features), and clinical trials. At diagnosis, 28% of colon cancer members have Stage II disease. Approximately 1 in 3 (27%) stage II colon cancer members receive adjuvant treatment.