PET gains medical and political traction in cancer prognosis

November 16, 2009
Greg Frieherr
Greg Frieherr

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Greg Frieherr
Greg Frieherr

PET/CT is gaining recognition both medically and politically when it comes to sizing up cancer. And the timing for oncologists couldn’t be better.

PET/CT is gaining recognition both medically and politically when it comes to sizing up cancer. And the timing for oncologists couldn't be better.

Earlier this month, researchers at Thomas Jefferson University Hospitals reported at ASTRO 2009 that metabolic changes, seen on PET scans, may be early and accurate indicators of response to therapy for patients with non-small cell lung cancer. Last week, a peer-reviewed article by a team at Southern Illinois School of Medicine stated that PET/CT may help identify patients with head and neck cancer who need surgery six to eight weeks after they have received chemo and radiotherapy.

Also last week the Centers for Medicare and Medicaid Services approved the unrestricted reimbursement of PET for initial staging of cervical cancer.

Previous to this latest ruling, reimbursement for PET depended on whether other imaging modalities had uncovered evidence of metastatic spread of the disease outside the pelvis. A statement by SNM, the nuclear medicine society, noted that the strong body of evidence led the federal agency in charge of Medicare to conclude that PET can provide physicians with important information on how to treat patients with cervical cancer without the need for these restrictions.

These developments couldn't come at a better time for oncology. PET/CTs have spread throughout the medical community in the U.S., as unbridled efforts a few years ago to keep up with neighboring facilities led providers to acquire these scanners at an unprecedented rate. A spurt of technological innovation over the last couple of years has improved image quality and increased exam speed, which increased the unused capacity of this installed base.

At this nexus of scanner availability and existing demand, Medicare administrators are warming to the argument that this modality deserves wider reimbursement, just as medical research is uncovering new and better ways to use PET/CT.

The work done at Thomas Jefferson found that a rapid decline in metabolic activity, seen on PET scans taken after radiation therapy for non-small cell lung cancer, correlates with good local tumor control. In their study of 50 patients, Dr. Maria Werner-Wasik, associate professor of radiation oncology at Thomas Jefferson, and colleagues found that the risk of local failure to control the tumor decreased in relation to declines seen in a metabolic metric called maximum standardized uptake value (mSUV). When the pretherapy PET scan was compared with scans taken after therapy, patients who responded well to therapy showed a decline in mSUV of the primary tumor of 72% by the first post-therapy scan, 76% by the second scan, and 77% by the third scan.

The research team also found that a snapshot of metabolic activity taken before treatment was also an accurate-and potentially sobering-prognostic indicator. The higher the metabolic activity and greater the tumor size on a PET scan before treatment, they said, the more likely the patient will die from the cancer.

PET/CT now has also been shown to provide a look into how well patients with head and neck cancer are responding to chemo and radiotherapy. In the November issue of Archives of Otolaryngology-Head & Neck Surgery, Dr. James P. Malone, an associate professor of surgery at the Southern Illinois School of Medicine in Springfield, reports that PET/CT can help determine whether this initial therapy has done the job or if surgical resection of the tumor site and cervical lymph nodes is indicated to prevent tumor recurrence. An analysis of data from 31 patients with advanced-stage head and neck cancer treated with chemo- and radiotherapy led Dr. Malone and colleagues to conclude that not only does PET/CT provide an early prediction of treatment response but the modality detects distant metastases, which permits earlier intervention in patients with metastatic disease.