1.   Perhaps the most exciting of future possibilities for genetic intervention in cancer is the direct manipulation of oncogenes or tumour suppressor genes.

2.   Research into colorectal tumours has directly or indirectly contributed to the discovery of three new tumour suppressor genes.

3.   Various mutations in both oncogenes and tumour suppressor genes have been implicated heavily in the development of cancer.

4.   Tumour suppressor genes seem to be very important in colorectal carcinogenesis.

5.   Consequently, unlike other tumour suppressor genes, only one allele need be mutated to produce a phenotypic effect.

6.   The presence of other chromosomal deletions in colorectal cancer suggests that several more tumour suppressor genes have yet to be identified.

7.   Supplementation of tumour suppressor genes or the use of specific oncoprotein antagonists may inhibit tumour cell growth in vivo in the same way that they do in vitro.

8.   Mutations may result in the activation of oncogenes or the inactivation of tumour suppressor genes, leading to abnormal or unregulated cell growth.