Why randomized surgical oncology trials are so scarce

Trends in worldwide volume and methodological quality of surgical randomized controlled trials

OBJECTIVE

To assess worldwide trends in volume and methodological quality of published surgical randomized controlled trials (RCTs) over the past decade.

BACKGROUND

Randomized controlled trials are essential for clinical decision making. It has repeatedly been suggested that surgical RCTs are scarce and of mediocre quality.

METHODS

We systematically searched PubMed for surgical RCTs published in 1999 and 2009. Characteristics and risks of bias were extracted. Trials where compared between study years and geographical regions. Primary outcome was "low risk of bias," defined by all of the following: adequate allocation generation and concealment, intention-to-treat analysis, and adequate dropout handling.

RESULTS

The volume of published surgical RCTs increased by 50%, from 300 in 1999 to 450 in 2009. Volume increased in Europe (27% increase), Asia/Oceania (160% increase), and Africa/South America (416% increase) but decreased in North America (23% decrease), although the United States remained the country with the highest number of published RCTs. In 2009, methodological quality of surgical trials improved in terms of sample size calculation, adequate generation of randomization sequence, concealment of randomization sequence, and use of intention-to-treat analysis as compared with 1999 (P < 0.001 for all). The proportion of low risk of bias trials increased from 6% to 14% (prevalence ratio 2.59; 95% confidence interval 1.55-4.32). In 2009, the highest proportion of low risk of bias trials was from Europe (23%), whereas the lowest was from Asia/Oceania (5%).

CONCLUSIONS

Volume and quality of surgical RCTs improved although striking differences exist between continents and countries. Structured education in trial methodology, enforced adherence to existing guidelines, and improved research infrastructure may guide further improvements.

Secondary surgical cytoreduction for advanced ovarian carcinoma

BACKGROUND

We evaluated the effect of adding secondary cytoreductive surgery to postoperative chemotherapy on progression-free survival and overall survival among patients who had advanced ovarian cancer and residual tumor exceeding 1 cm in diameter after primary surgery.

METHODS

Women were enrolled within six weeks after primary surgery. If, after three cycles of postoperative paclitaxel plus cisplatin, a patient had no evidence of progressive disease, she was randomly assigned to undergo secondary cytoreductive surgery followed by three more cycles of chemotherapy or three more cycles of chemotherapy alone.

RESULTS

We enrolled 550 women. After completing three cycles of postoperative chemotherapy, 216 eligible patients were randomly assigned to receive secondary surgical cytoreduction followed by chemotherapy and 208 to receive chemotherapy alone. Surgery was declined by or medically contraindicated in 15 patients who were assigned to secondary surgery (7 percent). As of March 2003, 296 patients had died and 82 had progressive disease. The likelihood of progression-free survival in the group assigned to secondary surgery plus chemotherapy, as compared with the chemotherapy-alone group, was 1.07 (95 percent confidence interval, 0.87 to 1.31; P=0.54), and the relative risk of death was 0.99 (95 percent confidence interval, 0.79 to 1.24; P=0.92).

CONCLUSIONS

For patients with advanced ovarian carcinoma in whom primary cytoreductive surgery was considered to be maximal, the addition of secondary cytoreductive surgery to postoperative chemotherapy with paclitaxel plus cisplatin does not improve progression-free survival or overall survival.