Longer treatment with cancer drug following removal of GI tumor results in improved survival

Among patients with a high risk of recurrence of a gastrointestinal stromal tumor following surgery for its removal, patients who received imatinib (a drug to treat certain cancers) for 3 years instead of 1 had improved recurrence-free survival and overall survival, according to a study in the March 28 issue of JAMA.

"Gastrointestinal stromal tumors (GIST) are usually found in the stomach or the small intestine but can occur at any site along the gastrointestinal tract and rarely elsewhere within the abdominal cavity," according to background information in the article. "The malignancy potential of GIST varies from negligible in micro GIST to aggressive cancer." Treatment with imatinib for 12 months after surgery has improved recurrence-free survival (RFS), although recurrence of GIST is common during the first years following discontinuation of treatment, suggesting that 12 months of administration may be too short a time period.

Heikki Joensuu, M.D., of the Helsinki University Central Hospital, Helsinki, Finland, and colleagues examined whether adjuvant (following surgery) imatinib treatment for longer than 3 years might be beneficial compared to 1 year of administration for GIST patients who were considered to have a high risk of GIST recurrence. The randomized trial included patients with KIT (a gene)-positive GIST removed at surgery who were entered into the study between February 2004 and September 2008. Two hundred patients were assigned to the 12-month group and 200 to the 36-month group from 24 centers located in Finland, Germany, Norway, and Sweden. Patients were randomized to receive imatinib, 400 mg per day, orally for either 12 months or 36 months, started within 12 weeks of surgery.

The researchers found that recurrence-free survival was longer in the 36-month group compared with the 12-month group (5-year RFS, 65.6 percent vs. 47.9 percent). Fewer patients assigned to 36 months of imatinib administration died during the follow-up as compared with those assigned to the 12-month group (12 vs. 25, respectively), and overall survival was longer in the 36-month group (5-year survival, 92.0 percent vs. 81.7 percent, respectively).

The authors also found that a larger proportion of patients discontinued imatinib in the 36-month group for reasons other than GIST recurrence compared with the 12-month group (51 [25.8 percent] vs. 25 patients [12.6 percent], respectively; the reasons were adverse effect, patient preference, tumor histology not GIST, and other or unspecified reason). Almost all study patients had at least 1 adverse event recorded; most events were graded mild in severity.

Gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are fairly rare tumors of the GI tract. These tumors start in special cells found in the wall of the GI tract, called the interstitial cells of Cajal (ICCs), or in very early cells that can develop into ICCs. ICCs are part of the autonomic nervous system, the part of the nervous system that regulates body processes such as digesting food. ICCs are sometimes called the "pacemakers" of the GI tract because they send signals to the muscles in the digestive system, telling them to contract to move food and liquid through the GI tract.