Feb 2025
8m 47s
In this JCO Article Insights episode, Peter Li summarizes “Neoadjuvant Modified Infusional Fluorouracil, Leucovorin, and Oxaliplatin With or Without Radiation Versus Fluorouracil Plus Radiation for Locally Advanced Rectal Cancer: Updated Results of the FOWARC Study After a Median Follow-Up of 10 Years,” by Dr. Jianwei Zhang et al. published on December 13, 2024.
TRANSCRIPT
Peter Li: Hello and welcome to the JCO Article Insights. I'm your host Peter Li and today we will be discussing the Journal of Clinical Oncology article, “Neoadjuvant Modified Infusional Fluorouracil, Leucovorin, and Oxaliplatin With or Without Radiation Versus Fluorouracil Plus Radiation for Locally Advanced Rectal Cancer: Updated Results of the FOWARC Study After a Median Follow-Up of 10 Years,” by Dr. Jianwei Zhang et al.
For a reminder to the audience, the FOWARC study is a Chinese-based study that looked into the treatment of locally advanced rectal cancers with neoadjuvant chemotherapy based regimens with or without radiation. This study was first published back in 2019 where the three-year data showed no difference in three-year disease-free survival over survival between the three study arms. As a reminder of what those arms were, there were one historical control and two interventional arms. The control arm used 5-FU with radiation therapy with five cycles of 5-fluorouracil with radiation during cycles two to four followed by surgery and then seven cycles adjuvantly. Their first interventional arm was the same as the control arm with the addition of oxaliplatin on day 1of each cycle. And lastly, the third arm was FOLFOX only for four to six cycles followed by surgery and then six to eight cycles adjuvantly completing about a total of 12 weeks of chemotherapy.
They recruited about 495 patients with 165 patients randomized to each arm. They were relatively well balanced by age, clinical staging and distance from the anal verge. Median age was about mid-50s with a slight male predominance and patients were primarily stage 3 with 20% to 30% being stage 2. About 30% had clinical T4 disease and about 25% had clinical N2 disease. Median follow up time was 122.5 months or 10 years and their follow up endpoints were disease-free survival, overall survival and local recurrence, and they also performed subgroup analyses based on post surgical pathological staging. Survival was analyzed using Kaplan-Meier method with a significant threshold of p being less than 0.05. About 451 patients actually underwent surgery, which is about 91% of patients. The main reason for not going through surgery was due to refusal but one was due to toxicity and two were due to disease progression in the control arm. Follow up loss rate was about 10% in each group. Now looking at their primary endpoints in their initial study, local recurrence was about 8.8% in the control arm versus 7.9% in the FOLFOX radiation group versus 9.2% in the FOLFOX only group. Distant metastasis was about 30% in each arm and the sites of metastases were primarily in the lung and liver.
Now, following up with 10 years, there were only three new events in the chemoradiation group with local recurrence happening at 10.8% in the control arm versus 8% in the FOLFOX RT group versus 9.6% in the chemo only group. These findings were not statistically significant. In their subgroup analysis by pathological staging, they found that pathological CR or complete response had a lower rate of local recurrence compared to those with increasing pathological staging coming in at 3% versus 4.3% versus 11.6% versus 15.8% in pCR versus Stage 1, 2, 3 respectively. And they found no difference in each stage with each interventional arm. Looking at long term survival their 10-year disease free survival showed 52.5% in the 5-FU radiation group versus 62.6% in the FOLFOX RT group versus 60.5% in the chemotherapy only group with no statistically significant difference between three groups. By pathological staging, they found improved 10-year disease survival in those who achieved pathological complete response versus those who did not with 84.3% in the pCR group versus 78.7% versus 56.8% versus 27.7% in the stage 1 versus 2 versus 3 group. And again they found no statistical significance difference between each arm.
Now looking at the 10-year overall survival rates between the three arms, in the control arm the 10-year overall survival was 65.9% versus 72.3% in the FOLFOX RT group versus 73.4% in the chemo only group. By pathological stage, again, they showed a statistically significant difference in those who achieved pCR versus those who had pathological stage 1 to 3 disease with overall survival being 92.4% in those who achieved pCR versus 84.9% versus 68.6% versus 48.8% in stage 1, 2, 3 respectively. Now in the discussion, authors mentioned that with a median follow up of 10 years, FOLFOX alone had similar disease-free survival, local recurrence and distant metastasis and overall survival compared to those who received neoadjuvant chemoradiation, justifying the omission of radiation without compromising results or outcomes for each patient. There were no differences in subgroup analysis for disease free survival local recurrence or overall survival based on pathological staging. There were only three new events compared to the last follow up, with local recurrence happening only in the chemo radiation groups. Local recurrence rates at 10 years was about 10%. Compared to other clinical trials such as CAO, ARO or AIO-94, the rate of local recurrence was similar to those historical trials.
The authors also compared their findings to the PROSPECT study which looks at the use of total neoadjuvant chemo radiation versus chemotherapy alone, which boasted only about a 2% local recurrence rate. But as a reminder, high risk locally advanced rectal cancers were excluded, mainly those with T4 or N2 disease, which may explain the difference in terms of local recurrence in the PROSPECT versus this study. Another finding is that pathological complete responses are also an important prognostic marker with lower 10-year local recurrence rate, disease-free survival and overall survival with worse outcomes with increased pathological staging. Distant metastasis rates were still at 30%, with the most common site being lung then liver then lymph nodes consistent with other historical studies. Chemotherapy seemed to be better at reducing liver mets than lung metastasis per their findings. In their post hoc analysis of their own study, chemo radiation was also associated with higher incidence of low anterior resection syndrome and persistent ostomy compared to chemotherapy alone, meaning that they had better quality of life with the chemotherapy only approach.
In conclusion, a chemotherapy only approach can be safe and a feasible treatment for locally advanced rectal cancer without compromising outcomes. Omission of radiation may reduce the risk of overtreatment and improve quality of life for some of these patients. However, this does not necessarily exclude the role of radiation as it may still play a role in a response escalation approach for those who do not respond to chemotherapy alone.
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