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Guest column

Scan may predict likelihood of ovarian cancer survival

By V. UPENDER RAO
Published October 3, 2005

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At the 52nd annual meeting of the Society of Nuclear Medicine, Dr. Norbert Arvil, associate professor of radiology and chief of nuclear medicine at the University of Pittsburgh, presented the results of a study that showed a correlation between improvement on serial positron emission tomography scans and survival of ovarian cancer patients treated with preoperative chemotherapy.

The study consisted of 33 patients with a median age of 60 years. Twenty-three had stage III, and 10 had stage IV ovarian cancer with massive ascites (fluid in the abdomen). They were treated with chemotherapy before definitive surgery. Patients underwent PET scanning at base line and after the first and third cycles of chemotherapy. Out of 26 patients studied with PET scans after the first cycle of chemotherapy, 15 patients showed a response, and 11 did not. In addition to PET scans, patient's response to treatment was accessed by clinical criteria such as:

--Measurement of residual tumor volume of less than 4 cms;

--Regression of peritoneal studding of cancer;

--Changes in the tumor marker CA 125;

--Repeat biopsies looking for tumor response to chemotherapy.

The results of these clinical criteria of response and the results of the PET scans were correlated with the patients' survival after chemotherapy. The results showed no significant correlation of patient survival with the four clinical criteria enumerated above. However, there was a significant correlation of overall patient survival and the metabolic response seen on PET scans performed after the first and third cycle of chemotherapy.

A previously agreed criterion of 20 percent decrease in the FDG uptake on the PET scan was used to define response. Those patients who showed such a response after the first cycle of chemotherapy had a survival of 38.3 months, while those who did not register a response on the PET scan achieved a survival of only 23.1 months. After one year 93 percent of responders and 81 percent of nonresponders survived. By the end of the second year, 73 percent of responders and 45 percent of nonresponders were alive, and by the end of the third year 60 percent of responders and only 18.2 percent of nonresponders were alive.

These results suggest that sequential PET scanning can predict response to chemotherapy and likelihood of survival of patients much better than other clinical criteria that are currently used. Arvil said that such early prediction can help decide which patients can continue chemotherapy without surgical intervention and which patients need immediate surgery and other, more aggressive treatments.

Such early information regarding response to chemotherapy can aid treatment decisions. However, the results of this study are based on only a few patients. Larger prospective randomized studies are needed to validate these findings. Until such a time, serial PET scanning is not recommended as a tool of response assessment for routine cases.

--V. Upender Rao, M.D., FACP, practices at the Cancer and Blood Disease Center in Lecanto.

[Last modified October 3, 2005, 01:15:16]

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