According to results recently published in Lancet Oncology, chemotherapy for Stage II colorectal cancer appears to provide a modest improvement in survival.
Colorectal cancer remains the second leading cause of cancer-related deaths in the United States. Stage II (or B) colorectal cancer refers to cancer that has penetrated the wall of the colon but has not spread to any nearby lymph nodes and is not detectable elsewhere in the body.
Depending on specific characteristics of the cancer, 60–75% of patients are cured without evidence of recurrence following surgery alone. However, despite undergoing complete surgical removal of the cancer, disease recurs in 25–40% of patients with Stage II colorectal cancer.
Typically, cancer recurs because small amounts of cancer that had spread outside the colon were not removed by surgery. These cancer cells cannot be detected with currently available tests. Such undetectable areas of cancer outside the colon are referred to as micrometastases, and they cause the relapses that follow surgical treatment. In order to improve the cure rate achieved with surgical removal of the cancer, an effective treatment is needed to cleanse the body of micrometastases.
The effectiveness of chemotherapy administered following surgery (adjuvant chemotherapy) for Stage II colorectal cancer has been debated; results regarding its ability to improve survival for this group of patients have been inconsistent. Adjuvant chemotherapy is used to kill micrometastasis to reduce recurrences and ultimately improve outcomes. But because no clear results regarding adjuvant chemotherapy in Stage II colorectal cancer have been established, researchers continue to evaluate this treatment approach.
Researchers recently conducted a clinical study to further evaluate adjuvant chemotherapy in the treatment of Stage II colorectal cancer. The study, referred to as the QUASAR study, included 3,239 patients with Stage II colorectal cancer who were treated with surgery followed by adjuvant chemotherapy (consisting of a 5-fluorouracil-based regimen) or with no further treatment. Median follow-up was five and a half years.
- The five-year survival was improved by 3.5% among patients who received adjuvant chemotherapy compared with those who did not receive adjuvant therapy.
- The risk of recurrences was reduced by approximately 22% among patients treated with adjuvant chemotherapy.
The researchers concluded that adjuvant chemotherapy in Stage II colorectal cancer is associated with a modest though significant improvement in survival.
Patients diagnosed with Stage II colorectal cancer may wish to speak with their physician regarding their individual risks and benefits of chemotherapy.
Reference: QUASAR Collaborative Group. Adjuvant chemotherapy versus observation in patients with colorectal cancer: a randomized study. Lancet Oncology. 2007;370:2020-2029.