Proving Its Worth: Interventional Oncology Squeezes & Freezes Tumors

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Tumors_1329925643.jpg - Shrinking Tumor
Image credit: Society of Interventional Radiology
Interventional oncology techniques are gaining traction with liver and prostate cancers, particularly when other therapies have not proven successful. However, redirecting the tide of traditional treatment may be the biggest obstacle for these new therapies to overcome in their quest toward greater acceptance.

Squeezing Liver Tumors

Approximately 18,500 cases of primary liver cancer are diagnosed annually in the U.S.—of which hepatocellular carcinoma (HCC) is the most common—and the figures are estimated to reach 34,000 cases by 2019, according to a 2006 Society of Interventional Radiology (SIR) position statement. The first line of treatment options for those with primary liver cancer is transplantation and surgical resection.

Unfortunately, more than 75 percent of HCC patients are not candidates for either treatment, explains John F. Angle, MD, director of the vascular and interventional radiology division at University of Virginia (UVA) Health System in Charlottesville, Va. Also, chemotherapy is largely ineffective in this patient subset.

When transplant and resection are not an option, large facilities, such as UVA Health System and Johns Hopkins Hospital in Baltimore, present those cases to the liver tumor board, which typically includes transplant surgeons, medical oncologists, hepatologists, radiation oncologists and interventional radiologists.

“All the specialists come together to determine the best treatment plan for each individual patient,” says Angle. “This multidisciplinary approach is truly the best approach.” He adds that they always try to direct patients to transplant or resection first, and then proceed to alternative treatment options.

The most common alternative interventional radiology options are chemoembolization and radiofrequency (RF) ablation—which can be applied simultaneously.

The newest alternative to hit the block is radioembolization, using intra-arterial yttrium-90 (Y-90) microspheres (TheraSphere, MDS Nordion), which combines the radioactive isotope Y-90 into microspheres that deliver radiation into a tumor. In a study presented at the 2010 SIR meeting, Y-90 resulted in 58 percent of tumors being down-staged from T3 to T2 after long-term follow-up, and 32 of the 291 patients were considered transplantable after outpatient treatment.  

Chemoembolization has been proving its worth for years in research, but that has only recently started to impact clinical practice. In a 2002 study in The Lancet, which examined 112 randomized cirrhotic patients with unresectable liver cancer, the one-year survival rate was 82 percent for the chemoembolization arm and 63 percent for the conservative treatment. A more recent 2011 Journal of Clinical Oncology article reported that the combination of sorafenib and chemoembolization in patients with unresectable HCC is well tolerated and safe.

Chemoembolization and radioembolization are “fairly similar treatments because they both use the artery as the roadway to the tumor,” says Jean-Francois Geschwind, MD, division chief of vascular and interventional radiology at Johns Hopkins. “They both effectively kill tumors, but the toxicity side effect with chemoembolization can be fairly significant and patients are admitted overnight, whereas with Y-90, patients can have a same-day discharge and the toxicity and side effects are less severe.” In the 2010 SIR trial evaluating Y-90, treatment-related adverse effects were considered mild: fatigue (57 percent), vague abdominal pain (23 percent) and nausea/vomiting (20 percent).

Both treatments follow a similar imaging protocol: the patient undergoes a baseline MRI, the procedure is guided by angiography and an MRI exam after the procedure assesses the response.

Chemoembolization beads and Y-90 are less toxic and have fewer side effects for patients, which has led to greater acceptance among referring physicians, “because they know their patients will tolerate the treatment better,” according to Marshall E. Hicks, MD, division head of diagnostic imaging at the MD Anderson Cancer Center in Houston.

Freezing Prostate Cancer

Prostate cancer is the third most common cause of death from cancer in men and management decisions often depend on the degree of spread or stage of the cancer.

At the 2009 SIR meeting, Gary M. Onik, MD, presented trial results on a series of 120 men who underwent focal cryoablation during a 12-year period. After a mean follow-up of 3.6 years, 93 percent of these men had stable prostate-specific antigen levels and no evidence of cancer. While presenting his results, Onik advocated for the use of cryoablation as a “first-line option.”

However, not everyone agrees that ultrasound ablation should be employed as a front-line treatment yet, including Hicks, who cautions that much of the research is preliminary. “While Dr. Onik has been a champion of this approach in the early stage of prostate cancer, it is not being used routinely in clinical practice,” he adds.

Interventional techniques may have greater promise in the later stages of the prostate care continuum. Cancer recurrence rates after surgical resection can be as high as 25 to 30 percent. Some men continue to have detectable residual prostate cancer after surgical removal and radiation treatment.

David A. Woodrum, MD, PhD, an interventional radiologist at the Mayo Clinic in Rochester, Minn., and his urologist colleague, Lance A. Mynderse, MD, have been collaborating to develop new treatment options for the subgroup of prostate cancer patients who have undergone surgery or radiation treatment, and have limited options after cancer recurrence. Woodrum predicts that at least 75,000 new patients annually are looking for additional therapy options for recurrent prostate cancer after surgical removal of the prostate.

At the 2010 SIR meeting, they presented data on four men who had undergone MR-guided laser interstitial thermal therapy or cryoablation to treat prostate cancer recurrence after surgical removal of the prostate. Woodrum and Mynderse have successfully treated nine patients in the last year who have not had recurrence in short-term follow-up, and these treatments have preserved their baseline sexual and urinary functions. Currently, they are focusing research solely on cryoablation, as opposed to both hot and cold techniques.

Woodrum and Mynderse concur about the preference of MR to guide and assess the prostate. “Prostate cancer recurrences are best seen by MR, which are only sometimes seen by ultrasound,” says Mynderse. “MRI also is superior to ultrasound during the cryoablation procedure because ultrasound can only portray the front edge of ice and not the back edge. With MRI, we can monitor the proximity of vital structures and see the extent of the treatment zone—simultaneously and in real time.”

While these methods are proving their worth in research, even esteemed institutions like MD Anderson are only beginning to use them. “The slow uptake doesn’t mean that these newer methods don’t have merit, but they are confronted by decades of conventional therapies, similar to ablation in the liver and kidneys in the late 1980s and early 1990s before it gained more widespread acceptance,” Hicks points out.

Thus, more time and data may be required before these techniques hit the mainstream, but in the interim, advocates and researchers will continue to monitor their patients for the most appropriate entry point in the interventional oncology continuum.