The U.S. published the most interventional oncology (IO) articles of any country between 1996 and 2008, while Japan and China completed far more clinical research trials as the growth of U.S. research slowed, according to a study published in the November edition of Radiology.

With more than 12 million estimated deaths from cancer worldwide each year and well over half a million of these deaths in the U.S., IO procedures have been a growing area of research and treatment on top of the more standard chemotherapy, radiotherapy and surgery, the article's authors pointed out.

The study reviewed 3,801 interventional oncology studies published worldwide between 1996 and 2008. The authors pulled articles from the National Library of Medicine MEDLINE with subject heading terms "catheter ablation," "embolization, therapeutic" and "chemoembolization, therapeutic." All other articles were excluded, as were articles that did not have neoplasm, carcinoma or sarcoma as a subtopic. Several other search criteria were employed to limit the findings to IO as well.

Of the 3,801 studies classified as IO research, the most common tumor type studied was liver, accounting for nearly 63 percent of all IO articles, followed by kidney studies (10 percent), lung tumor studies (5 percent), bone tumors (5 percent), and pancreatic and bone cancer studies each comprising about 2 percent of the world's IO research.

"The downside to a heavy liver cancer focus is a relative de-emphasis of IO research targeting tumors in other organs. Lung and colorectal cancers, in particular, contribute to substantial global mortality and morbidity, yet few IO articles on these cancers have been published," wrote authors Daniel S. Chow, MD, of the David Geffen School of Medicine at the University of California Los Angeles, and Michael W. Itagaki, MD, MBA, of the University of Washington Medical Center in Seattle.

Researchers from the United States published the most IO articles with 847, or 22.3 percent of the world total. Japan followed with 19 percent of IO articles, with China and Germany producing 10.3 and 7.2 percent of the total number of articles, respectively.

Japan and China published the largest number of clinical research studies, with 19 and 18 percent of the 398 clinical trials published between 1996 and 2008. The United States and Italy followed with 13 and 11 percent of clinical trials, respectively.

The United States led the world in the number of review articles published, 187 out of the total of 507. Germany followed with approximately 10 percent of the total.

"Although the United States contributed the most IO articles," the authors stated, "it does not enjoy the unparalleled dominance in IO research that it does in radiology overall. Research in IO is clearly a global effort, with many nations making contributions.

"Overall," Chow and Itagaki continued, "worldwide IO publications grew steadily. Articles numbered 115 in 1996 and 501 in 2008."

The National Institutes of Health, led by the National Cancer Institute, funded nearly 10 percent of U.S. studies, with the rate of funding growing by 1.4 studies per year. However, "[c]omparing total U.S. government (including NIH and other U.S. government agencies) and non-U.S. government support for IO and general radiology showed that IO studies were consistently less likely to receive funding," the authors found. Nearly 19 percent of radiology articles received NIH funding, the authors discovered, compared to just 9.6 percent of IO studies. Chow and Itagaki said that while NIH funding was still significant, it "is unlikely to have a substantial effect on total U.S. publication numbers."

"Unlike the mild global slowdown in IO publications, U.S. growth is slowing notably. In contrast, publication growth in Japan and Taiwan is linear, and growth is exponential in South Korea and much of Europe," Chow and Itagaki observed.

The authors acknowledged that their research might not account for all IO studies undertaken between 1996 and 2008. For one, the authors restricted their sources to MEDLINE as well as their searches to particular subject and title keywords. Additionally, the researchers said that unpublished research, failed trials, new techniques and devices as well as meeting presentations were all excluded from their research.

Chow and Itagaki expressed optimism for the growth of U.S. interventional oncology research in light of the $10.4 billion additional dollars allocated to the NIH as part of the American Recovery and Reinvestment Act of 2009, which declares cancer research to be a top priority.