Concept of chemoprevention in colorectal cancer

Table 1 Use of aspirin in average risk subjects and colonic neoplasia risk reduction

Study	n	Aspirin dose (mg/AD)	Study duration (yr)	Relative risk reduction (95% CI)
Thun et al[13]	622 424	100 mg3	≥ 1	0.58 (0.36-0.93)1
				0.61 (0.38-0.97)2
Gann et al[14]	22071	325	5	1.15 (0.80-1.65)1
Cook et al[15]	39876	100	10	0.97 (0.77-1.24)2
Stürmer et al[16]	22071	325	12	1.03 (0.83-1.28)
Giovannucci et al[17]	47900	325	4	0.54 (0.34-0.84)1
Paganini-Hill et al[18]	13979	325	7-10	1.38 (NR)1
Chan et al[19]	89446	100	10	0.62 (0.44-0.86)2
Friis et al[20]	29470	325	6	0.9 (0.70-1.10)1
García-Rodríguez et al[21]	12005	325	> 2	0.9 (0.8-1.1)
Reeves et al[22]	845	100	> 5	0.79 (0.46-1.36)2
Juarranz et al[23]	502	325	NR	0.32 (0.09-1.10)
La Vecchia et al[24]	3248	325	5	0.7 (0.50-1.00)
Kune et al[25]	1442	325	NR	0.57 (0.41-0.79)
Suh et al[26]	2704	325	6	0.33 (0.15-0.72)
Slattery et al[27]	3051	325	> 5	0.7 (0.6-0.8)

¹Males;

²Females;

³Daily; AD: Alternate day dosage; CI: Confidence interval; NR: Not reported.

Table 2 Role of aspirin in colorectal neoplasia risk among patients with past tumour

Trials	n	Aspirin dose	Duration (yr)	Relative risk (95% CI)
Baron et al[28]	1121	81/325 mg	1	0.96 (0.81-1.13)
Benamouzig et al[29]	272	160/300 mg	1	0.82 (0.7-0.95)
Greenberg et al[30]	864		4	0.52 (0.31-0.89)
PPSG[31]	1905	< 325 mg	4	0.82 (0.65-1.02)
		> 325 mg		0.54 (0.3-0.96)
Sandler et al[32]	492	> 15 tab/month	5	0.84 (0.5-1.43)
Breuer-Katschinski et al[33]	442	> 4 tab/week	< 5	0.91 (0.32-2.64)
			> 5	0.09 (0.01-0.82)

CI: Confidence interval; PPSG: Polyp prevention study group.

Table 3 Colorectal cancer and the potential carcinogenic role of various factors

CRC category (% diagnosed with CRC)	Intervention strategies
Sporadic CRC (75%)	Screening Programmes
	Detection and removal of polyps (age > 50 yr)
	Role of chemoprevention
	NSAIDs/Aspirin
	5-aminosalicylate
	Dietary and lifestyle factors
	Good: low protein, high fibre, low fat, micronutrients, exercise
	Bad: alcohol, tobacco, obesity
Familial syndromes + miscellaneous (25%)	Screening colonoscopy
	Other: Aspirin and NSAIDs, 5-ASA

CRC: Colorectal cancer; NSAIDs: Non steroidal anti-inflammatory drugs; 5-ASA: 5-aminosalicylates; IBD: Inflammatory bowel disease.