What is the cure rate of stage 2 colon cancer with high-risk features without adjuvant chemotherapy (chemotherapy given in addition to primary treatment)?

From the Guidelines

The cure rate for stage 2 colon cancer with high-risk features without adjuvant chemotherapy is approximately 68%-83% with surgery alone. Without chemotherapy, patients with high-risk stage 2 colon cancer face a higher recurrence risk compared to those who receive adjuvant treatment. High-risk features include T4 tumors (extending through the bowel wall), poorly differentiated histology, lymphovascular or perineural invasion, bowel obstruction or perforation at presentation, fewer than 12 lymph nodes examined, or positive margins. For these patients, adjuvant chemotherapy typically improves survival by about 3-5% in absolute terms, as seen in the 2022 ASCO guideline update 1. The standard adjuvant chemotherapy regimens that would improve outcomes include FOLFOX (5-fluorouracil, leucovorin, and oxaliplatin) for 3-6 months or capecitabine with or without oxaliplatin.

Some key points to consider in the management of stage 2 colon cancer with high-risk features include:

• The addition of oxaliplatin to fluoropyrimidine-based adjuvant chemotherapy is not routinely recommended, but may be offered as a result of shared decision making 1.
• Patients with mismatch repair deficiency/microsatellite instability tumors should not be routinely offered adjuvant chemotherapy; if the combination of mismatch repair deficiency/microsatellite instability and high-risk factors results in a decision to offer adjuvant chemotherapy, oxaliplatin-containing chemotherapy is recommended 1.
• The decision to forgo chemotherapy should be carefully considered, weighing the modest survival benefit against potential side effects like neuropathy, fatigue, and gastrointestinal symptoms.
• Regular surveillance remains crucial for patients who don't receive chemotherapy, including regular CEA testing, CT scans, and colonoscopies to detect any recurrence early, as supported by the 2022 ASCO guideline update 1 and the 2013 NCCN guidelines 1.

It's also important to note that the prognosis after resection is relatively favorable, with an estimated 5-year disease-free survival rate of approximately 68%-83% with surgery alone, as stated in the 2022 ASCO guideline update 1. However, the recurrence rate in high-risk stage II patients is 40%-50%, which is similar to the rate in stage III patients, for whom adjuvant therapy is recommended 1.

From the Research

Cure Rate of Stage 2 Colon Cancer with High Risk Features without Adjuvant Chemotherapy

• The cure rate of stage 2 colon cancer with high risk features without adjuvant chemotherapy is not directly stated in the provided studies. However, the studies suggest that adjuvant chemotherapy can improve overall survival (OS) in patients with high-risk stage II colon cancer 2, 3, 4.
• A study published in 2015 found that adjuvant chemotherapy was associated with improved OS in high-risk patients, but no significant benefits were observed with regard to recurrence-free survival (RFS) or disease-specific survival (DSS) 2.
• Another study published in 2020 found that adjuvant chemotherapy was associated with improved OS regardless of high-risk features, tumor location, age, gender, comorbidity index, chemotherapy regimen, or type of colectomy 3.
• A study published in 2018 found that chemotherapy was associated with improved overall survival only among patients with T4 as the single high-risk feature or combinations involving T4 4.
• A study published in 2023 found that multiple high-risk features in stage II colon cancer predict worse survival than lymph node metastasis, and chemotherapy is associated with adverse cause-specific survival in patients with stage II disease 5.

High-Risk Features and Survival

• The presence of multiple high-risk features in stage II colon cancer is associated with poorer survival 4, 5.
• T4 tumors and their combination with other high-risk features achieve the most survival benefit with adjuvant therapy 4.
• The type and number of high-risk features should be taken into consideration when recommending adjuvant chemotherapy in stage II colon cancer 4.

Adjuvant Chemotherapy

• Adjuvant chemotherapy is recommended in patients with stage II colon cancer with high-risk features despite lacking conclusive randomized trial data 3.
• The use of adjuvant chemotherapy decreases with advancing age, and elderly patients receive more single-agent than multi-agent chemotherapy 3.
• Major predictors of adjuvant chemotherapy use include pT4 status, evaluation of <12 lymph nodes, high-grade tumors, positive resection margins, age <65 years, left-sided tumors, and low comorbidity score 3.