Mismatch repair status predicts survival after adjuvant treatment in stage II colon cancer patients

Improved Risk-Stratification Scheme for Mismatch-Repair Proficient Stage II Colorectal Cancers Using the Digital Pathology Biomarker QuantCRC

PURPOSE

There is a need to improve current risk stratification of stage II colorectal cancer to better inform risk of recurrence and guide adjuvant chemotherapy. We sought to examine whether integration of QuantCRC, a digital pathology biomarker utilizing hematoxylin and eosin-stained slides, provides improved risk stratification over current American Society of Clinical Oncology (ASCO) guidelines.

EXPERIMENTAL DESIGN

ASCO and QuantCRC-integrated schemes were applied to a cohort of 398 mismatch-repair proficient (MMRP) stage II colorectal cancers from three large academic medical centers. The ASCO stage II scheme was taken from recent guidelines. The QuantCRC-integrated scheme utilized pT3 versus pT4 and a QuantCRC-derived risk classification. Evaluation of recurrence-free survival (RFS) according to these risk schemes was compared using the log-rank test and HR.

RESULTS

Integration of QuantCRC provides improved risk stratification compared with the ASCO scheme for stage II MMRP colorectal cancers. The QuantCRC-integrated scheme placed more stage II tumors in the low-risk group compared with the ASCO scheme (62.5% vs. 42.2%) without compromising excellent 3-year RFS. The QuantCRC-integrated scheme provided larger HR for both intermediate-risk (2.27; 95% CI, 1.32-3.91; P = 0.003) and high-risk (3.27; 95% CI, 1.42-7.55; P = 0.006) groups compared with ASCO intermediate-risk (1.58; 95% CI, 0.87-2.87; P = 0.1) and high-risk (2.24; 95% CI, 1.09-4.62; P = 0.03) groups. The QuantCRC-integrated risk groups remained prognostic in the subgroup of patients that did not receive any adjuvant chemotherapy.

CONCLUSIONS

Incorporation of QuantCRC into risk stratification provides a powerful predictor of RFS that has potential to guide subsequent treatment and surveillance for stage II MMRP colorectal cancers.

Adjuvant Therapy for Stage II Colon Cancer: ASCO Guideline Update

PURPOSE

To develop recommendations for adjuvant therapy for patients with resected stage II colon cancer.

METHODS

ASCO convened an Expert Panel to conduct a systematic review of relevant studies and develop recommendations for clinical practice.

RESULTS

Twenty-one observational studies and six randomized controlled trials met the systematic review inclusion criteria.

RECOMMENDATIONS

Adjuvant chemotherapy (ACT) is not routinely recommended for patients with stage II colon cancer who are not in a high-risk subgroup. Patients with T4 tumors are at higher risk of recurrence and should be offered ACT, whereas patients with other high-risk factors, including sampling of fewer than 12 lymph nodes in the surgical specimen, perineural or lymphatic invasion, poorly or undifferentiated tumor grade, intestinal obstruction, tumor perforation, or grade BD3 tumor budding, may be offered ACT. The addition of oxaliplatin to fluoropyrimidine-based ACT is not routinely recommended, but may be offered as a result of shared decision making. Patients with mismatch repair deficiency/microsatellite instability tumors should not be routinely offered ACT; if the combination of mismatch repair deficiency/microsatellite instability and high-risk factors results in a decision to offer ACT, oxaliplatin-containing chemotherapy is recommended. Duration of oxaliplatin-containing chemotherapy is also addressed, with recommendations for 3 or 6 months of treatment with capecitabine and oxaliplatin or fluorouracil, leucovorin, and oxaliplatin, with decision making informed by key evidence of 5-year disease-free survival in each treatment subgroup and the rate of adverse events, including peripheral neuropathy.Additional information is available at www.asco.org/gastrointestinal-cancer-guidelines.

Stage migration resulting from inadequate number of examined lymph nodes impacts prognosis in stage II colon cancer after radical surgery

PURPOSE

We evaluated the impact of examined lymph node (ELN) number on the prognosis of stage II colon cancer after radical surgery and developed a novel prognostic scoring system by combining primary tumor extension (pT) and ELN number for reclassification of stage II colon cancer.

METHODS

Three cohorts of patients diagnosed with colon cancer between 2004 and 2010 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. Univariate and multivariate analyses were performed to evaluate the relationship between factors and patients' survival including cause-specific survival (CSS) and overall survival (OS). Survival curves from subgroups were plotted by the Kaplan-Meier method and compared by the log-rank test.

RESULTS

Cohort 1 and cohort 2 consisted of 13,960 and 5312 stage II colon cancer patients, respectively. Cohort 3 consisted of 4713 stage III patients. Factors including ELN, age, and pT were found to be associated with patients' survival in cohorts 1 and 2. Patients who were older or with smaller tumors were more likely to experience inadequate ELN. Patients with a higher score, as calculated by the novel scoring system, showed worse survival. Compared with stage III colon cancer patients, stage II patients with high scores had a comparable or even worse survival than stage IIIA and IIIB patients.

CONCLUSION

Inadequate ELN leads to understaging in stage II colon cancer and predicts inferior prognosis. Our analyses show that the novel prognostic scoring system, consisting of combined pT and ELN, quantified stage migration effect and can be applied to the reclassification of stage II colon cancer.

Duration of FOLFOX Adjuvant Chemotherapy in High-Risk Stage II and Stage III Colon Cancer With Deficient Mismatch Repair

Background

We evaluated the impact of 3 months of mFOLFOX6 adjuvant chemotherapy or surgery alone in comparison with 6 months of mFOLFOX6 on disease-free survival (DFS) in deficient mismatch repair (dMMR) colon cancer (CC) patients.

Methods

This retrospective study identified a cohort of patients with high-risk stage II and III dMMR CC who underwent curative surgery between May 2011 and July 2019. DFS was compared using the Kaplan-Meier survival methods and Cox proportional hazards models. Propensity-score matching was performed to reduce imbalance in baseline characteristics.

Results

A total of 242 dMMR CC patients were identified; 66 patients received 6 months of mFOLFOX6, 87 patients received 3 months of mFOLFOX6, and 89 patients were treated with surgery alone. The 3-year DFS rate was 72.8% in 3-month therapy group and 86.1% in 6-month therapy group, with a hazard ratio (HR) of 2.78 (95CI%, 1.18 to 6.47; P= 0.019). The difference in DFS between surgery alone group and 6-month therapy group was also observed but was nonsignificant (HR= 2.30, 95%CI, 0.99 to 5.38; P=0.054). The benefit of 6-month therapy in DFS compared with 3-month therapy group was pronounced for patients with stage III (HR=2.81, 95%CI, 1.03 to 7.67; P=0.044) but not for high-risk stage II patients. Propensity score matched analysis confirmed a DFS benefit in the 6-month therapy group.

Conclusion

This study suggested that a 6-month duration of mFOLFOX6 adjuvant chemotherapy in dMMR CC patients may be associated with improved DFS compared with 3-month therapy, particularly in patients with stage III. The observational nature of the study implies caution should be taken in the interpretation of these results.

Association between local immune cell infiltration, mismatch repair status and systemic inflammatory response in colorectal cancer

Background

Systemic inflammatory response in colorectal cancer (CRC) has been established as a prognostic factor for impaired cancer-specific survival, predominantly in patients with right-sided tumors. On the other hand, defective mismatch repair (dMMR) tumors, primarily located in the right colon, are known to have favorable survival and dense local immune infiltration. The aim of this study was to see if there is any form of relationship between these seemingly diverse entities.

Methods

Complete clinical and long-term survival data were retrieved for 316 CRC patients operated at Helsinki University Hospital between the years 1998 and 2003. Tissue microarrays were prepared from surgical specimens and further processed and analyzed for local immune cell infiltration using multispectral imaging with a Vectra quantitative pathology imaging system and Inform software. Multiplex immunohistochemistry was applied using antibodies against CD66b, CD8, CD20, FoxP3, CD68 and pan-Cytokeratin. After exclusions, data on immune infiltration were available for 275 patients. Mismatch repair status was determined by immunohistochemistry.

Results

CRP was seen to be an independent predictor of cancer-specific survival but not overall survival in uni- and multivariable (HR 1.01 (1.00–1.02); p = 0.028) analyses of non-irradiated patients. There was no significant difference in CRP according to mismatch repair status, but all cases (n = 10) with CRP ≥ 75 mg/l had proficient mismatch repair (pMMR). There was a significant negative correlation between intratumor stromal infiltration by T-regulatory FOXP3⁺ cells and CRP (p = 0.006). There was significantly lower intratumor stromal infiltration by FOXP3⁺ cells (p = 0.043) in the right colon compared to the rectum, but no significant difference in CRP (p = 0.44). CRP was not a predictor of overall survival (HR 0.99, 95% CI 0.98–1.01) nor cancer-specific survival in irradiated patients (HR 0.94, 95% CI 0.94–1.02).

Conclusions

There was a significant negative relationship between SIR, defined as an elevated CRP, and intratumor stromal infiltration by T-regulatory FOXP3⁺cells. This and the fact that all cases with a CRP > 75 mg/l had pMMR suggests that SIR and dMMR are independent entities in CRC. Indeed, the general lack of difference in CRP between cases with dMMR and pMMR may be evidence of overlap in cases with a less pronounced SIR.