Intraperitoneal chemotherapy underused among patients with ovarian cancer

CHICAGO — Although the use of intraperitoneal chemotherapy has increased significantly over the past decade, it remains underutilized in treatment of women with ovarian cancer, according to study results presented at the ASCO Annual Meeting.

Prior studies have confirmed that intraperitoneal (IP) chemotherapy confers a significant, long-term survival advantage compared with IV chemotherapy. The GOG-172 randomized trial showed IP chemotherapy extended survival by 16 months, prompting the NCI to issue a clinical alert in 2006 recommending IP for treatment of ovarian cancer.

However, little data exists with regard to how extensively IP chemotherapy has been adopted in clinical practice.

Alexi A. Wright

Alexi A. Wright, MD, MPH, assistant professor and medical oncologist at Dana-Farber Cancer Institute and colleagues, conducted a prospective cohort study to assess the frequency of and factors associated with IP chemotherapy use.

The study included 603 women with stage III, optimally cytoreduced ovarian cancer treated at National Comprehensive Cancer Network institutions.

Researchers used the Cochrane-Mantel Haentzel test to examine trends in IP chemotherapy over time. They used multivariate logistic regression models to assess associations between patient characteristics and IP chemotherapy use. They used multivariable logistic regression and propensity-score analyses to assess associations between treatment modality, OS and adverse events.

Study results showed IP chemotherapy use increased from 0% to 33% between 2003 and 2006. Usage increased to 50% in 2007-2008, then decreased to 43% between 2009 and 2012.

At treatment initiation, 29% of patients who received IP chemotherapy underwent the regimen used in GOG-172, and 28% received IP chemotherapy on a clinical trial.

“What we found interesting was that IP chemotherapy was not prescribed as recommended by GOG 172 for most patients. In fact, 43% of patients received intraperitoneal chemotherapy off-trial with modifications from the start,” Wright told HemOnc Today. “Doctors reduced doses or substituted less toxic chemotherapy drugs in an attempt to minimize the toxicities that their patients faced.”

Researchers determined 5-year OS were 57% for those who received IP chemotherapy and 44% for those who received IV chemotherapy (HR=0.69; 95% CI, 0.5-0.94). They also determined patients who received IP chemotherapy were more likely to switch to IV chemotherapy due to toxicity than the other way around (adjusted OR=2.01; 95% CI, 1.3-3.12).

Results of adjusted analysis showed patients who were younger, those who had fewer comorbid conditions and those who were enrolled on a clinical trial were more likely to receive IP chemotherapy (P≤.01 for all).

Treatment at an NCCN center was independently associated with receipt of IP chemotherapy. However, the adjusted rates of patients who underwent IP chemotherapy varied considerably by site (range, 16% to 71%; P<.001).

“Even at institutions where all the necessary resources and training were in place, less than half of eligible patients who meet the study criteria actually received [intraperitoneal chemotherapy]. Among the patients who did, there were huge variations in what they received, which was not what had been originally tested under GOG-172,” Wright said. “This variation in use between institutions suggests that there are significant physician’ preferences and institutional biases that are driving the care that patients receive, which may not necessarily reflect what patients want.”

For more information:

Wright AA. Abstract #358. Presented at: ASCO Annual Meeting; May 30-June 3, 2014; Chicago.

Disclosure: Wright reports no relevant financial disclosures.