ROLE FOR PET FOR MANY CANCER TYPES

Impact of PET Scanning Consistent Across All Cancer Types

December 2, 2008 — Scanning with positron emission tomography (PET) scanning has an impact on the intended management of patients with cancer in approximately one third of cases, and new data suggest that this impact is consistent across all cancer types.

The results come from the National Oncologic PET Registry (NOPR), and the latest data are reported in the December issue of the Journal of Nuclear Medicine.

"Although the effectiveness of PET may differ somewhat between individual cancers, it's in the same ballpark," says coauthor Barry Siegel, MD, professor of radiology at Mallinckrodt Institute of Radiology in St. Louis, Missouri. "This result was a little unexpected, but it leads us to believe that a continual parsing of PET's usefulness, cancer by cancer and indication by indication, for purposes of reimbursement does not make clinical sense."

At present in the United States, the Centers for Medicare & Medicaid Services (CMS) restricts the reimbursement of PET scans for only 9 cancer types. The cancers that are covered include non–small-cell lung cancer, esophageal cancer, colorectal cancer, head and neck cancer, lymphoma and melanoma (all for diagnosis, staging, and restaging), breast cancer (for restaging and treatment monitoring), thyroid cancer (for restaging under very specific circumstances), and cervical cancer (for initial staging if conventional imaging result is negative for extrapelvic metastasis).

NOPR was launched in 2006 in response to a proposal from the CMS to expand coverage for PET to other cancers. In this registry, patients are covered under the CMS evidence development program to undergo PET scans for many other cancers and indications, including cancers of the ovary, uterus, prostate, pancreas, stomach, kidney, and bladder. The latest results show that PET has a similar impact across all of these cancer types. Although there was some variation, particularly a high impact on multiple myeloma, the differences across the cancer types were not statistically significant, and overall there was an impact in 38% of cases.

"We found that it did not vary significantly, and that the changes in treatment plans for rare cancers — such as stomach cancer — clustered around the same one-third mark as the more common cancers," said lead author Bruce Hillner, MD, professor of medicine at Virginia Commonwealth University in Richmond. "As a result, we believe that the coverage for PET in the staging, restaging and detection of recurrent cancer should be handled the same across the board," he said in a statement.

"The data from NOPR as well as from other studies, the totality of the PET literature in cancer, show that it is a very effective tool for imaging in cancer, and that it should be approved broadly," Dr. Siegel said in an interview with Medscape Oncology. There is no restriction on the use of computed tomography or magnetic resonance imaging by cancer type, he pointed out, and the use of PET scanning across all cancer types "is just as logical," he added.

"Basically, what we were trying to do is to inform CMS policy," he explained. "We wanted to collect data to show that, if you were thinking of picking and choosing, then you should cover this cancer and maybe not this one, but the truth of the matter is that when you look at the data it's hard to say what to include or exclude," he said. "Our recommendation is to include all cancers. PET is as mature a cancer imaging tool as CT and MRI, and I just don't understand why we don't have a level playing field."

The CMS is expected to decide on the reimbursement of PET scans in other cancers soon. A draft is expected on January 10, 2009, and after another public comment period, the final National Coverage Determination will be made on April 9, 2009.

Dr. Siegel told Medscape Oncology that he was cautiously optimistic. "Our sense is that the CMS has a good understanding of our data, and I think there will be some additional coverage, and I have my fingers crossed for global coverage."

Changes in Intended Management After PET Scans

The latest report assessed the impact of PET for 18 cancer types, none of which are currently on the list for CMS reimbursement. This study looked at 3 distinct indications: initial staging, restaging, and detection of suspected recurrence. Only patients who had pathologically confirmed cancer were included; hence, this study excluded the use of PET for diagnosis. It also excluded patients in whom PET was being used to monitor response to chemotherapy or radiotherapy (this indication has also been studied in NOPR, and results have recently been published online in Cancer).

Table. Impact of PET Scanning on Intended Management of Cancer

Type of Cancer	No. of PET Scans	% Cases With Change in Intended Management
Prostate	5309	35.1
Ovary	4509	41.4
Bladder	3578	37.8
Pancreas	3314	39
Stomach	2025	36.9
Small-cell lung cancer	2983	41.2
Kidney	2877	35.8
Uterus	2869	36.5
Myeloma	1784	48.7
Connective tissue	1350	36.4
Nonmelanoma skin	1057	31.4
Liver and intrahepatic bile ducts	1038	42.9
Cervix	984	32.7
Gallbladder	806	39.7
Other female genitalia	709	37.1
Thyroid	629	35.6
All other	4042	36.6
TOTAL	40,863	38.0

As a result of seeing the PET scans, clinicians changed their intended management of the cancer as follows:

• From nontreatment to treatment in 30% of cases
• From treatment to nontreatment in 8% of cases
• Change in goal from curative to palliative (or vice versa) in 14% of cases
• Change to supportive care or observation in 15.1% of cases
• Major change (eg, from surgery to chemotherapy) in 8.6% of cases
• Minor change (eg, addition or deletion of a mode of therapy) in 23.3% of cases

"We believe that the NOPR results show the impact of PET to be strikingly consistent for a wide range of cancers," the researchers conclude. "Accordingly, the use of PET in management for patients with known cancer should not be restricted by cancer type or testing indication."

Several recent publications have confirmed and validated these findings, Dr. Siegel commented to Medscape Oncology. In particular, several multicenter prospective trials have been conducted in Australia (J Nucl Med. 2008;49:1451-1457, 1593-1600) that provide "very strong process validation" of our data from the registry, he said.