Gideon Steinbach, Patrick M Lynch et al
The Effect of Celecoxib, a cyclooxygenase-2 inhibitor, in familial adenomatous polyposis.
New Eng J Med. Vol.342, June 29, 2000, pg. 1946.
Patients with familial adenomatous polyposis have a nearly 100 percent risk of colorectal cancer. Chemo-preventive effects of NSAIDs may be related to their inhibition of cyclooxygenase-2.
Authors studied the effect of celecoxib, a selective cyclooxygenase-2 inhibitor, on colorectal polyposis in patients with familial adenomatous polyposis. In a double-blind, placebo-controlled study, 77 patients were randomly assigned to treatment with celecoxib (100 or 400 mg twice daily) or placebo for 6 months. Patients underwent endoscopy at the beginning and end of the study. The number and size of the polyps were determined from photographs and videotapes, the response to treatment was expressed as the mean percent change from base line.
It was concluded that in patients with familial adenomatous polyposis, 6 months of twice daily treatment with 400mg of celecoxib, leads to a significant reduction in the number of colorectal polyps.
Christopher C, Zielinski and Michael Hejna
Warfarin for cancer prevention.
New Eng Jr Med. Vol.342, No.26, June 29, 2000, pg.1991.
Clear evidence has been provided of an association between idiopathic thromboembolism and development of cancer. The risk is significantly higher among patients less than 65 years of age than among those who are 65 or older.
Heparin, aspirin and other NSAIDs and warfarin have been used experimentally for prevention and treatment of various tumours in animals and humans. There are impressive data that suggest that aspirin and other NSAIDs reduce the risk of colorectal cancer probably by suppressing the synthesis of cyclooxygenase-2 and proinflammatory prostaglandins.
A prospective randomised Veterans Affairs Co-operative Study demonstrated that the use of warfarin led to a statistically significant prolongation of the time to disease progression and improved survival among patients with small-cell lung cancer but not among patients with non-small cell lung cancer or cancer of the head, neck, prostate or colon.
Schulman and Lindmarker report in this journal the effect of anticoagulants on the development of cancer. It is likely that anticoagulants were not acting on preexisting, clinically overt tumours but, rather were preventing the development of new cancerous lesions. This interpretation originated in a previous investigation that studied the optimal duration of anticoagulant therapy after venous thromboembolism and concluded that 6 months was superior to 6 weeks.
This study should raise the awareness of the risk of certain cancers in patients with idiopathic thromboembolism. The necessity of appropriate follow up in these patients is clear. Wafarin needs to be studied in controlled clinical trials, with the aim of assessing prevention rather than treatment of cancer. Persons with genetic or environmental risk for the specific cancers should be considered for such studies. Warfarin could be a drug to be added to the armamentarium of chemoprotective agents.
Sam Schulman and Per Lindmarker
Incidence of cancer after prophylaxis with warfarin against recurrent venous thromboembolism.
New Eng Jr Med. Vol.342, June 29, 2000, pg. 1953
The length of time after an episode of venous thromboembolism during which the risk of newly diagnosed cancer is increased is not known, and whether vitamin K antagonists have an antineoplastic effect is controversial.
In a prospective, randomized study of the duration of oral anticoagulation (6 weeks or 6 months) after a first episode of venous thromboembolism, patients were questioned annually about any newly diagnosed cancer. After a mean follow up of 8.1 years, authors used the Swedish Cancer Registry to identify all diagnoses of cancer and causes of death in the study population. The observed numbers of cases of cancer were compared with expected numbers based on national incidence rates, and the standardized incidence ratios were calculated.
The conclusion was that the risk of newly diagnosed cancer after a first episode of venous thromboembolism is elevated during at least the following 2 years. Subsequently, the risk seems to be lower among patients treated with oral anticoagulants for 6 months than among those treated for 6 weeks.