Two case studies have described what is believed to be the first reported successful use of stereotactic body radiation therapy for an often deadly complication of kidney cancer. These provide an important potential new avenue for treatment of these types of tumors, which are resistant to traditional radiation therapies and difficult to manage even with surgery, the current standard of care.
“Our case studies showed similar survival with the use of stereotactic radiation therapy compared with surgery,” said lead author Raquibul Hannan, MD, PhD, Assistant Professor of Radiation Oncology and co-leader of the Kidney Cancer Program at the Harold C. Simmons Comprehensive Cancer Center in Dallas, Texas. “This result is important because people with this disease have a traditionally poor prognosis and few options.”
The stereotactic ablative radiation therapy (SABR) was used to treat inferior vena cava tumor thrombus (IVC-TT) that reached the heart, a complication of kidney cancer in which the tumor extends into the system of veins that return blood to the heart. An estimated 4% to 36% of kidney tumors are associated with IVC-TT, according to the study, published in Cancer Biology & Therapy (2015; doi: 10.1080/15384047.2015.1026506).
Currently, surgical removal is the only proven effective treatment, but it is considered extremely difficult and delicate. It has high rates of complications and cancer recurrence, with mortality rates for patients who undergo the surgery being as high as 10%. No current alternatives exist for patients who are not candidates for surgery.
“For these reasons, finding new therapies such as stereotactic radiation therapy are desperately needed,” Hannan said. “This innovative proof-of-principle was a critical first step for determining whether our approach will ultimately prove to be effective.”
Kidney cancer is a common and often deadly malignancy, with more than 63,900 new cases and 13,800 deaths predicted in the United States in 2014. Its incidence is rising at a rate of 4% annually.
In addition, IVC-TT can be difficult to diagnose because patients may have no symptoms or a wide variety of symptoms that can be attributable to many other conditions. Left untreated, IVC-TT can lead to severe complications including pulmonary tumor embolus (tumor clots in the lung), Budd-Chiari syndrome (a serious liver condition), and even fatality.
These case studies, one a case of recurrent and another a case of unresectable IVC-TT, demonstrate that SABR can be an effective treatment. The reported survival times of 18 months and 24 months were comparable to standard surgical outcomes and both improved symptomatically, and did not experience any acute or late treatment-related toxicity, the researchers reported. UT Southwestern’s kidney cancer team hopes to follow up with a study to evaluate the application of SABR for IVC-TT in conjunction with surgery.
Stereotactic body radiation therapy was originally developed to treat brain cancer. It relies on highly advanced imaging, treatment planning, and radiation delivery technology to deliver an extremely potent dose with extreme precision from multiple angles and it has been shown to offer better cure rates for many cancers, particularly in cancers that have metastasized.