Tiré de la presse Dimanche le 28 octobre 2011
La prise d’aspirine à long terme préviendrait le cancer colorectal chez des personnes à très haut risque héréditaire, selon une étude publiée vendredi, montrant chez elles une réduction de plus de moitié du nombre de cas observés.
Cette nouvelle étude, publiée dans The Lancet, vient confirmer les effets protecteurs de l’aspirine contre le cancer colorectal, avancés par de précédentes recherches.
L’étude concerne des personnes atteintes du syndrome de Lynch qui présentent un risque élevé de développer ce cancer intestinal ainsi que d’autres cancers (ovaires, estomac…).
Ce syndrome génétique rare ne concerne que 3% de tous les cancers colorectaux. Les personnes touchées par ce syndrome doivent faire l’objet d’une surveillance médicale dès l’âge de 20 ans avec des examens par endoscopie colorectale tous les deux ans.
Sur les 861 participants, la moitié a pris 600 mg d’aspirine par jour pendant au moins deux ans, l’autre moitié un placebo (produit inactif).
La première analyse des données en 2007 n’a pas montré de différences entre les deux groupes. Mais en 2010 il y avait 34 cas de cancer colorectal dans le groupe placebo contre 19 dans le groupe aspirine, soit une réduction de 44% de l’incidence de ce cancer.
En centrant l’analyse sur ceux qui avaient pris l’aspirine pendant au moins deux ans (60% environ du total), les effets de l’aspirine apparaissent plus prononcés : on observe une réduction de 63% de l’incidence du cancer colorectal avec 23 cas dans le groupe placebo contre seulement 10 dans celui qui a pris l’aspirine.
L’effet commence à être visible cinq ans après le début de la prise d’aspirine, selon la revue.
Des études complémentaires sont nécessaires pour déterminer la dose optimale d’aspirine et la durée du traitement, selon le Pr John Burnes (Royaume-Uni, Université de Newcastle) et ses collègues.
Selon une étude publiée l’an dernier dans la même revue, l’aspirine à petite dose prise sur le long terme réduirait considérablement la mortalité due à un certain nombre de cancers courants (colon, prostate, poumon…). Ainsi, sur une vingtaine d’années, la réduction du risque de décès par cancer serait de 40% pour le cancer colorectal.
Primary prevention of colorectal cancer with low-dose aspirin in combination with endoscopy: a cost-effectiveness analysis.
Source
Nuovo Regina Margherita Hospital, Rome, Italy.
Abstract
ObjectiveLow-dose aspirin reduces colorectal cancer (CRC) incidence and mortality. Recently, the aspirin effect has been shown to occur primarily in the proximal colon. Colonoscopy has been either less effective or ineffective in the proximal compared to the distal colon. The authors assessed the cost-effectiveness of adding low-dose aspirin to a simulated screening with colonoscopy or sigmoidoscopy.DesignA Markov model comparing the strategies of 10-year colonoscopy or sigmoidoscopy screening and the combination of either of the two with low-dose aspirin in 100 000 subjects aged 50 years until death was constructed. Proximal and distal CRC prevention rates with endoscopy or aspirin were extracted from the literature. Screening and aspirin prevention were simulated to stop at 80 years. The cost of aspirin and aspirin-related complications, as well as aspirin-related mortality, was included. Incremental cost-effectiveness ratios between the different strategies were calculated. Sensitivity and probabilistic analyses were also performed.ResultsThe addition of low-dose aspirin to colonoscopy and sigmoidoscopy screening increased the CRC death prevention rate from 68% and 39% to 81% and 69%, respectively. Lifetime aspirin-related mortality appeared to be 0.1%. Because of the substantial reduction in CRC care, the addition of aspirin to colonoscopy and sigmoidoscopy screening was cost-effective (incremental cost-effectiveness ratio: US$5413 per life-year saved) and cost saving (US$278 per person), respectively. When the proximal CRC prevention rate with colonoscopy was increased 56% to 73% from the baseline, the addition of aspirin was no longer cost-effective. The addition of aspirin to colonoscopy and sigmoidoscopy was a cost-effective strategy in 52% and 94% of the scenarios at probabilistic analysis.ConclusionsWhen assuming a suboptimal efficacy of endoscopy in preventing CRC, the addition of low-dose aspirin may be an effective and cost-effective strategy, mainly because of its high efficacy in preventing proximal CRC.
Prevention by daily soluble aspirin of colorectal adenoma recurrence: 4-year results of the APACC randomised trial.
Source
AP-HP, Avicenne Hospital, Paris-13 University, Bobigny, France.
Abstract
BackgroundAspirin inhibits colorectal carcinogenesis. In a randomised double-blind placebo-controlled trial, daily soluble aspirinsignificantly reduced recurrence of colorectal adenomas at 1-year follow-up. In this study the results of daily intake of low-doseaspirin on polyp recurrence at 4-year follow-up are presented.Methods272 patients (naive for chronic aspirin use) with colorectaladenomas were randomly assigned to treatment with lysine acetylsalicylate 160 mg/day (n=73) or 300 mg/day (n=67) or placebo (n=132) for 4 years. The primary endpoints were adenoma recurrence and adenomatous polyp burden at year 4, comparingaspirin at either dose with placebo. The same endpoints were also assessed at year 1 or 4 (last colonoscopy performed for each patient).ResultsAt the final year 4 colonoscopy the analysis included 185 patients (55 receiving aspirin 160 mg/day, 47 aspirin 300 mg/day and 83 placebo). There was no difference in the proportion of patients with at least one recurrent adenoma between patients receiving aspirin at either dose and those treated with placebo (42/102 (41%) vs 33/83 (40%); NS) or in the adenomatous polyp burden (3.1±5.8 mm vs 3.4±6.2 mm; NS). Also, the proportion of patients with at least one advanced recurrent adenoma did not differ (10/182 (10%) in the aspirin group vs 7/83 (7%) in the placebo group; NS).ConclusionDaily low-dose aspirin decreased adenoma recurrence significantly at 1 year but not at year 4. This discrepancy might be explained by a differential effect of aspirinaccording to the natural history of the polyp.
Aspirin use, body mass index, physical activity, plasma C-peptide, and colon cancer risk in US health professionals.
Source
Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA. xuehong.zhang@channing.harvard.edu
Abstract
Aspirin use decreases colon cancer risk, but this association may vary among population subgroups. The aspirin-colon cancerassociation was evaluated according to body mass index and physical activity in 1,701 incident colon cancer cases diagnosed during follow-up of 139,310 participants for up to 26 years in 2 US prospective cohort studies that began in 1980 and 1992, respectively. Whether plasma C-peptide levels modified the association was examined by using a nested case-control design (n = 384 cases, 749 controls). Multiplicative and additive interactions were tested. Body mass index did not modify the association; pooled multivariable relative risks for regular aspirin use versus nonuse ranged from 0.74 to 0.75 in the normal weight and obese groups (test for multiplicative interaction, P = 0.75; test for additive interaction, P = 0.66). Pooled multivariable relative risks for regular aspirin use were 0.86 (95% confidence interval (CI): 0.66, 1.11) in the low and 0.67 (95% CI: 0.58, 0.77) in the high physical activity groups with no interaction evident on either the multiplicative or additive scale (P > 0.10). Plasma C-peptide levels also did not modify the aspirin-colon cancer association, with multivariable relative risks of 0.74 (95% CI: 0.50, 1.10) for the low and 0.65 (95% CI: 0.46, 0.92) for the high group. Reductions in colon cancer risk associated with aspirin use were not significantly modified by body mass index, physical activity, or plasma C-peptide level in this study.
