Those in the stage IV group who were given post-surgery adjuvant chemotherapy were likely to live an average of nearly 9 more months than did those who did not have chemotherapy after radiation (22 vs. 13), while those given radiation therapy saw an increase in survival by 19 months (29 vs. 10). These increases did not affect stage I-III patients, who had a similar rate of survival regardless of additional therapies after their surgery (24 vs. 25 months).
One possible explanation for why additional therapy made little difference in survival for stage I-III patients is that, given that the tumors did not spread as widely, the surgical procedures were likely to be more effective at removing most of the disease, according to Dr. Tella.
“One of the possibilities is that surgeons were able to get the whole mass out,” Dr. Tella hypothesized in response to a question from attendees. “On the other hand, patients with stage IV ACC may be more likely to have more presence of metastases and so would benefit more greatly from the removal of the primary tumor and then also additional therapy.”
Investigators noted that because of the structure of the registry, they were unable to determine the initiation and duration of chemotherapy, as well as doses of radiation therapy received by the patient.