A newly devised risk score may help identify which patients with acute venous thromboembolism (VTE) are most likely to have occult cancer and where they are likely to have it, according to a report published online in CHEST.

Although VTE is known to occur before an occult cancer becomes symptomatic in a minority of patients, clinicians don’t agree on which patients with VTE should be screened for occult cancer or on how extensive that screening should be. Some favor a basic screening with only a clinical history, physical exam, simple lab tests, and a chest X-ray, while others advocate a more thorough work-up to improve the patient’s chance for a cure. “The potential benefits and harms of such screening are controversial, partly because there is little evidence” concerning which patients are at highest risk and which cancer types/sites should be assessed, said Luis Jara-Palomares, MD, PhD , of the medical surgical unit of respiratory diseases, Virgen del Rocio Hospital, Seville, Spain, and his associates.

Dr. Jara-Palomares and his associates devised a prognostic score by assigning points to the variables they found to be most significantly associated with occult cancer. For example, male sex was accorded 1 point, chronic lung disease or a high platelet count was accorded 1 point, age over 70 years or anemia was accorded 2 points, and postoperative or prior VTE was accorded negative 2 points. The incidence of occult cancer was significantly lower among patients whose total score was 2 points or less (5.8%) than among those whose total score was 3 points or higher (12%).

The mean age of these study participants was 63 years, and approximately half were women. A total of 444 (7.6%) were diagnosed as having cancer at 1-24 months after presenting with VTE. Most of these cancers were discovered within 6 months of the VTE.

Patients who had occult cancer were significantly more likely than those who did not to be male and older than 70 years of age; to have chronic lung disease, an elevated platelet count, and/or anemia; and to have a history of recent surgery and/or prior VTE.

The percentage of VTE patients who had occult cancer increased with advancing age, from 2%-3% in the youngest age group (younger than 50 years) to 8%-12% in the oldest age group (older than 70 years). Among men with occult cancer, the most frequently affected sites were the lung (26%), prostate (17%), and colon/rectum (10%). Among women, the most frequent types of cancer were colorectal (19%), breast (12%), uterine (9.1%), hematologic (8.6%), pancreatic (7.6%), and stomach (6.6%).

Overall, more than half of the men who had occult cancer had cancer affecting the lung, prostate, or colon/rectum, while two-thirds of the women who had occult cancer had cancer affecting the colon/rectum, breast, or abdomen. “This is important because [cancer] screening is not necessary in all VTE patients, but any information suggesting [which] patients are at increased risk and [which] sites are more common may be of help to decide the most appropriate work-up for each patient,” the investigators noted.

To determine which patients are most likely to have occult cancer and which cancer types are most likely to develop, the investigators analyzed data from RIETE (the Computerized Registry of Patients With Venous Thromboembolism), an international registry of more than 50,000 consecutive patients with confirmed acute VTE. They focused on 5,863 patients who presented with pulmonary embolism (34%), deep vein thrombosis (48%), or both disorders (18%) and were followed for at least 2 years for the development of cancer.

The accuracy of this risk scoring system must be tested further in a large validation cohort before it can be widely adopted. If it proves to be accurate, then patients with low total risk scores could forgo the expense, discomfort, and psychological stress of extensive cancer screening, Dr. Jara-Palomares and his associates said.

Men whose total score is 3 points or more could benefit from a rectal exam and fecal occult blood test to rule out colorectal cancer, a rectal exam and prostate-specific antigen test to rule out prostate cancer, and a chest CT to rule out lung cancer. Women whose total score is 3 points or higher could benefit from a fecal occult blood test to rule out colorectal cancer, a mammogram to rule out breast cancer, and abdominopelvic CT to rule out uterine, pancreatic, and stomach cancer, they noted.

The RIETE Registry is supported by an unrestricted educational grant from Sanofi Spain and by Bayer Pharma AG. Dr. Jara-Palomares reported having no relevant financial disclosures; his associates reported ties to Sanofi, Bayer, and LEO Pharma.


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