April 6, 2009

SIR Reporter’s Notebook
Radiology Today
Vol. 10 No. 7 P. 8

Editor’s Note: This article is based on material provided by the media relations staff of the Society of Interventional Radiology and the press conferences at its 34th annual meeting last month in San Diego.

Study Supports Cryoablation for Small Kidney Tumors
Freezing kidney tumors with a cryoprobe should be the first treatment option for all individuals with tumors that are 4 centimeters or smaller, according to two studies presented at the Society of Interventional Radiology’s 34th Annual Scientific Meeting in San Diego last month.

“Interventional cryoablation is as effective as laparoscopic surgery (partial nephrectomy), the current gold standard treatment, and laparoscopic cryoablation surgery for treating renal cell carcinoma,” said Christos Georgiades, MD, PhD, an interventional radiologist at Johns Hopkins Hospital in Baltimore. “We can eliminate a cancer that, once it metastasizes, can be notoriously difficult to treat and has a low chance of cure with a simple outpatient procedure.”

Cryoablation is approved by the FDA for treating soft tissue tumors such as renal cell cancer. The treatment is widely available in the United States and is usually covered by health insurance. Making patients aware of all their treatment options is important for making the best treatment decision for kidney cancer, which has been steadily increasing in this country over the past 30 years, Georgiades said.

First-Line Treatment
“Cryoablation is a great treatment option that doctors should discuss with patients early on,” he said.

Approximately 54,000 people are diagnosed with kidney cancer each year, with nearly 13,000 dying from it annually, according to recent statistics. More than 75% of individuals who are diagnosed with kidney cancer have small tumors that are discovered incidentally, and they are good candidates for cryoablation.

New Standard?
The Hopkins studies, examining the safety and efficacy of percutaneous cryoablation, show the treatment’s results. “Based on the results of our three-year study, we have shown that interventional cryoablation for kidney cancer should be the gold standard or the first treatment option for all patients whose tumors are 4 centimeters or smaller,” Georgiades said. “It should be a viable option for patients whose cancer is even larger than that. And ablation (or freezing) is a very effective option for patients who cannot or do not want to have surgery.”

Cryoablation’s efficacy rate is 100% in tumors up to 4 centimeters and nearly 100% in tumors up to 7 centimeters in size. Three localized, 10-centimeter tumors—large tumors that are typically removed surgically—were treated; in two cases, the tumor was successfully killed.

Georgiades noted that the success with the larger tumors is encouraging, but the number of cases is too small to draw conclusions about the procedure in patients with tumors larger than 4 centimeters.

“This news is especially significant for individuals with small tumors, since more than 75% of patients who are diagnosed with kidney cancer have tumors that are 4 centimeters or less in size,” Georgiades said. “These individuals can have their tumors treated completely, effectively, without surgery, with quicker recovery, and mostly on an outpatient basis. Whatever the definition of ‘cure’ is, these results come as close to it as possible.

“At Hopkins, interventional cryoablation is the first-line treatment for small tumors. Most of our patients go home the same day they receive treatment, with minimal limitation on regular activities. With laparoscopic kidney surgery, a patient remains in the hospital for several days, and recovery time can be from two to four weeks,” he added. “Our studies highlight how effective interventional radiology treatments can be not just for kidney cancer but for other kinds of cancers and other diseases as well.”

Researchers followed kidney cancer patients who had received cryoablation for three years to gauge the success of a kidney tumor treatment option, since most kidney tumors would be visible within one year with a CT scan or an MRI.

Broader Use
Georgiades said percutaneous cryoablation should not be limited, as it has been, to patients who have other diseases that make surgery very high risk, cannot undergo anesthesia, have borderline kidney function, may only have one kidney or multiple recurring tumors, or do not have any other option.

“There may be a bias in the medical community among surgeons, primary care doctors, and urologists that cryoablation works only for certain patients with small tumors. This is not the case,” he said.

“Traditionally, laparoscopic surgery has been the main treatment option for all renal cell cancers; it literally cuts the cancer out. The good news is that individuals no longer need to have a kidney partially or completed removed to treat their cancer,” Georgiades said.

When comparing the rate of complications between percutaneous cryoablation and surgery, Georgiades said that no patients who had cryoablation developed new or metastatic disease, and they had fewer complications. Cryoablation can be performed with minimal blood loss and through a tiny hole in the skin, which translates into significantly less pain, a shorter hospital stay, and more rapid recovery.

Unlike many cancer treatments, cryoablation can be repeated, if necessary. The most common complication is a bruise around the kidney that goes away by itself, according to Georgiades.

While studying cryoablation’s efficacy, researchers looked at 90 tumors in 84 patients. Efficacy was determined based on a tumor’s size at three-, six-, and 12-month postprocedural clinic visits and then yearly with follow-up imaging with CT or MRI scans. Both efficacy and three-year survival rates approached 100% overall.

While studying cryoablation’s safety, Georgiades studied the results of 101 percutaneous cryoablations on 91 patients who either couldn’t undergo surgery or chose the minimally invasive option.

Osteoplasty Relieves Metastatic Bone Disease Pain
Injecting bone cement to support weakened bones provides immediate and substantial relief of the painful effects of metastatic bone disease, according to researchers at the Society of Interventional Radiology’s Annual Scientific Meeting.

The procedure, called osteoplasty, can be coupled with heat or cold treatments to kill tumor nerves, if needed. Osteoplasty involves the injection of semiliquid polymethyl-methacrylate bone cement into a bone lesion under precise visual monitoring by CT or digital fluoroscopy imaging. The technique is similar to vertebroplasty commonly used to treat the pain of compression fractures.

“The immediate, good clinical results observed in our patients should encourage more widespread application of this palliative interventional radiology treatment,” said Giovanni C. Anselmetti, MD, an interventional radiologist at the Institute for Cancer Research and Treatment in Turin, Italy.

Bone metastases occur when cancer cells gain access to the blood stream, reach the bone marrow, begin to multiply, and then grow new blood vessels to obtain oxygen and food, which in turn causes the cancer cells to grow more and spread. For the most part, the goal of treating bone tumors is not curative but rather palliative by reducing pain, preventing additional bone destruction, and improving function.

“A patient’s quality of life can be severely affected when they have metastatic bone disease,” Anselmetti said. “Normal daily activities can become difficult when the metastases become painful, and many patients report that their sleep patterns change, appetite diminishes, and the need to take pain relief medications increases.”

Palliative Care
“Osteoplasty is not a first-line treatment,” Anselmetti added. “It is a highly effective, minimally invasive procedure that provides pain relief for patients not responding to conventional pain medication treatments. Metastatic bone disease patients who have no other options, who are in pain, who have short life expectancies, and who have dismal quality of life should be referred to interventional radiologists for osteoplasty treatment…”

Anselmetti believes osteoplasty can improve the quality of life for patients who have very large metastases and who are going to die because of their primary cancers.

Bone metastases can develop in conjunction with breast, bladder, kidney, lung, or other organ cancers. It occurs when cancer cells at an original site metastasize or travel to the bone. These metastases can become widespread throughout the skeletal system. Some bone metastases become painful because the tumor eats away at the bone, creating holes that make the bone thin and weak. As the bones are replaced with tumor, nerve endings in and around the bone send pain signals to the brain and the bone loses its functional strength. If left untreated, bone metastases can eventually cause the bone to fracture and seriously affect a patient’s quality of life. Each year, about 100,000 cases of bone metastasis are reported in the United States.

Along with osteoplasty to treat bone metastases, interventional radiologists may also use radiofrequency ablation or cryoablation to treat metastases. These treatments use heat or cold to desensitize the bone by killing the nerve endings in the vicinity of the metastasis. Once the nerve endings are dead, osteoplasty can be performed.

In the study, the average pain intensity score for patients based on the 11-point visual analog scale dropped significantly from 8.8 +/1.4 to 1.8 +/2.1 within 24 hours of osteoplasty.

Substantial Relief
“These patients experienced immediate and substantial pain relief,” Anselmetti said. “They did not require pain medication during the time of follow-up, and there were no clinically significant complications.”

Of 81 patients (59 women and 12 men), 64 (79%) were able to stop taking narcotic drugs for their pain, and 43 (53%) could stop taking other pain medication. In this study, pelvic, femur, sacrum, ribs, humerus, scapula, tibia, pubis, and knee bones were treated.

Anselmetti noted that osteoplasty provided effective pain regression for individuals with both painful bone metastases and benign lytic lesions that didn’t respond to conventional analgesic treatment.

IR Procedure Can Be Primary Treatment for Fixing AAA
Stent grafts can be used as first-line treatment for abdominal aortic aneurysm (AAA) repair, according to an eight-year study of 500 patients reported at the Society of Interventional Radiology’s annual meeting in San Diego last month. The endovascular treatment study shows reintervention rates comparable with those reported for open surgical repair.

“Our data show that the interventional radiology treatment can be chosen with confidence,” said Tarun Sabharwal, MD, an interventional radiologist at Guy’s and St. Thomas’ Hospitals in London. “This is good news for patients, many of whom do not want major abdominal surgery.”

Once an AAA has ruptured, the chances of survival are low, with 80% to 90% of all ruptured aneurysms resulting in death. Approximately 15,000 deaths are caused annually, and AAA affects as many as 8% of people over the age of 65; men are four times more likely to have it than women. These deaths can be avoided if an aneurysm is detected and treated before it ruptures.

Currently, endovascular repair is typically performed in elderly patients or those with comorbid conditions who were considered too sick for major surgery. Stent grafts were introduced about a decade ago, but it took time to assess their long-term durability. Early studies showed a higher rate of secondary interventions compared with surgery, prompting the recommendation that patients with endografts be monitored yearly with imaging, subjecting them to annual radiation.

Follow-Up Imaging Change
The new study prompted the researchers to advocate for revising current surveillance of patients’ stent grafts by CT scans to check for the delayed appearance of complications because of the added radiation risk the additional scans bring to patients.

Interventional radiologists analyzed the results of 453 patients aged 40 to 93 who underwent endovascular repair for AAA over an eight-year period. They studied the rate of secondary interventions to correct complications from a prior treatment and whether the need for repeat interventions could be predicted by surveillance imaging. “Most importantly, the overall rate of secondary interventions after endovascular repair was 7.2%, which compares favorably to surgery series,” Sabharwal said.

Complications of the endovascular treatment include possible movement of the graft after treatment or persistent blood flow into the aneurysm, which resumes the risk of its growth or rupture. Also, the graft must be monitored to ensure its continued function, and endoleaks may occur, causing blood to flow outside the endovascular graft. Researchers noted that 13 patients (2.8%) needed to be treated for this latter complication. The overall 30-day mortality rate for endovascular aneurysm repair was 3.3% compared with open surgery, which has an associated mortality rate ranging from 2% to 10.6%.

Additionally, researchers found that most complications were detected within the first three months after repair and that it was rare for CT scans to detect complications after that period of time.

Ultrasound After Three Months
“This suggests that CT surveillance protocols are not justified,” Sabharwal said. “If a three-month surveillance scan doesn’t demonstrate any abnormalities, then patients could be followed with routine ultrasound scanning to monitor for complications.”

In total, secondary interventions were performed in 33 patients (7.2%), of which six (1.3%) were CT scan surveillance detected.

“We have disproved myths about the durability and effectiveness of minimally invasive endovascular aneurysm repair,” Sabharwal said. “Our results, following patients over the past eight years, contradict reports of high rates of secondary interventions coupled with the need for prolonged CT scan surveillance. Endovascular repair reduces the risk of surgery, the amount of pain, and the number of complications, getting patients back to normal health more quickly than surgery. Its recovery time is measured in days to weeks, as opposed to surgery patients who take several weeks to months to recover.”

Sabharwal said endograft patients are often discharged the day after treatment, resuming normal activities within two weeks compared with six to eight weeks after surgery.

ABI Screening Helps Predict Heart Attack Risk
The use of common screening tests such as the ankle brachial index (ABI) can improve cardiac risk assessment compared with the Framingham Risk Score alone, according to researchers at the Society of Interventional Radiology’s annual meeting.

Screening ABI, used to diagnose peripheral arterial disease (PAD), is a painless test that compares the blood pressure in the legs to the blood pressure in the arms to determine how well the blood is flowing and whether further tests are needed. Combining such tests has the potential to prevent heart attacks in thousands of individuals not originally thought to be at high risk according to their Framingham score alone.

About 25% of all heart attacks or sudden cardiac deaths in the United States occur in individuals thought to be at low risk. Hoping to better assess these individuals, researchers analyzed data from the 1999-2004 National Health and Nutrition Examination Survey (NHANES). The survey provided a nationally representative cross-sectional survey of the U.S. population for 6,292 men and women aged 40 and older without a known history of heart disease, stroke, diabetes, or atherosclerotic vascular disease. It also included available data on standard cardiovascular risk factors and screening tests such as ABI, which is a comparative blood pressure test.

Additional Risk Factors
For the first time, researchers determined the prevalence of PAD in a large population of people not considered at high risk for cardiovascular disease based on their Framingham Risk Score alone. These novel risk factors not traditionally considered in the Framingham Risk Score were abnormal in up to 45% of those not considered to be at high risk for coronary heart events.

“This is significant news that can profoundly impact public health. If novel risk factors are shown to improve risk prediction, they could be very valuable because the prevalence of abnormal values is high in populations not known to have high risk,” said Timothy P. Murphy, MD, an interventional radiologist and director of the Vascular Disease Research Center at Rhode Island Hospital in Providence. “These simple tests like ABI screening have the potential to improve the accuracy of cardiovascular risk prediction and thereby have significant public health impact by helping identify people for intensive medical therapy and preventing heart attacks and strokes.”

Redefining Low Risk
While 91% of the NHANES group was considered at low or intermediate risk of cardiovascular disease, according to Framingham criteria alone, almost 45% of them were found to have at least one of three conditions: an abnormal ABI, an elevated plasma fibrinogen, or an elevated plasma C-reactive protein. “Even with abnormal ABI, which was the least prevalent of the three novel risk factors evaluated, that number translates into about 2.1 million Americans aged 40 and older who have no known history of heart disease, stroke, diabetes, or atherosclerotic vascular disease,” said Murphy. “There is also a good chance that ABI, which actually detects subclinical, already-established atherosclerotic disease, may actually perform better in terms of risk prediction than fibrinogen or C-reactive protein because it may be more specific.”