ADJUVANT CHEMOTHERAPY FOR COLORECTAL CANECR STILL HAS VALUE AFTER SIX MONTHS FROM SURGERY

Adjuvant chemotherapy has benefit even if given 6 months or more after resection for stage III colon cancer, a new retrospective study suggests.

"Compared to stage III colon cancer patients who did not receive adjuvant chemotherapy, patients who received chemotherapy within 6 weeks from the time of surgery were 56% less likely to die. Likewise, those who received therapy within 6 to 8 weeks were 55% less likely to die, and those who received chemotherapy within 8 to 12 weeks were 48% less likely to die," senior author Dr. John Migaly of Duke University Medical Center in Durham, North Carolina, told Reuters Health by email.

"More interestingly, even those patients who had a more pronounced delay in initiation of adjuvant chemotherapy experienced a survival benefit. Patients receiving chemotherapy at 12 to 24 weeks were 39% less likely to die and even those with a greater than 24-week delay were 32% less likely to die," Dr. Migaly said.

"This survival benefit was also seen in patients who had postoperative complication and in patients with multiple comorbidities. Most surprising is the finding that the benefit of chemotherapy was sustained at even greater than 24 weeks," he added.

Dr. Migaly and colleagues searched the 2006-2014 National Cancer Data Base (NCDB) for patients with single primary stage III adenocarcinoma of the colon and grouped patients according to their chemotherapy strategy.

Of the 72,057 patients included in the analysis, published online February 4 in the Journal of the American College of Surgeons, 20,807 omitted chemotherapy, 22,705 received chemo less than 6 weeks after resection, 15,412 at 6-8 weeks, 9,049 at 8-12 weeks, 3,595 at 12-24 weeks, and 489 more than 24 weeks after resection.

Compared to patients who did not receive chemotherapy, all of the groups who underwent chemotherapy had significantly lower hazard ratios (HRs) for death: <6 0.44="" 0.45="" 0.52="" 0.61="" 12-24="" 6-8="" 8-12="" after="" and="" resection="" weeks="">24 weeks (HR, 0.68).

"Many medical oncologists will not offer adjuvant chemotherapy in a delayed fashion, as there is a commonly held belief that giving chemotherapy outside of this perceived 'therapeutic window' has no benefit," Dr. Migaly said.

"This study contradicts traditional dogma and validates the utility of chemotherapy, even in a delayed fashion, up to and greater than 6 months after surgery. These results leave the door open for adjuvant chemotherapy in patients who have postoperative complications or comorbidities and are unable to undergo chemotherapy in the 'ideal' postoperative window," he noted.

Dr. Christine Veenstra, an assistant professor of internal medicine at the University of Michigan in Ann Arbor, told Reuters Health by email, "Through the inclusion of a comparison group of patients who did not receive any adjuvant chemotherapy, the authors have shown that, even when adjuvant chemotherapy initiation is delayed up to 6 months after surgery, there is still a survival benefit compared to no chemotherapy at all."

"Clinicians should therefore consider adjuvant chemotherapy for appropriate patients with stage III colon cancer, even in the face of post-surgical delays," advised Dr. Veenstra, who was not involved in the study.

Dr. Davendra Sohal, a medical oncologist at Cleveland Clinic in Ohio, said by email that even though this retrospective analysis may not be entirely practice-changing, it raises the question of whether physicians should ever decline adjuvant chemotherapy to patients outside the conventional treatment window.

"We sometimes see such cases where, due to comorbidities or surgical complications or both, adjuvant chemotherapy is delayed," said Dr. Sohal, who also was not involved in the study. "If that delay is more than 3 to 4 months, benefit comes into question, but this study shows otherwise."

"Since prospective studies in this setting are impractical, this is probably as best as we can get in terms of data," he pointed out. "Similar other databases, if available, should be queried to see if the findings are consistent."

SOURCE: http://bit.ly/2BrXwVs

J Am Coll Surg 2018.