ABSTRACT
Age is the most important risk factor for developing cancer and for dying from cancer. The risk of developing cancer within the following year changes little between the end of childhood and the age of 40 years. In women the risk increases earlier than in men, yet in both sexes the most dramatic increase is after the age of 60 years, as demonstrated in Fig. 25.1. Table 25.1 shows the risk of developing cancer within 5 years after treatment (i.e. the commonly practised follow-up time after radiotherapy for patients treated at the age of 50, 55, 60, 65, 70 or 75 years), assuming that cancer rates follow those found in the general population, as shown in Fig. 25.1. Since there is no convincing evidence that the development of one cancer protects against the development of another, we may conclude that, during the typical follow-up period of a patient treated for cancer with curative intent, a relatively large proportion of patients will present with a second cancer. This frequency will vary between 1 per cent and more than 10 per cent, depending on age and sex. The results of epidemiological studies described below indicate that in cancer patients, after curative radiotherapy, the increased lifespan of cured
patients is by far the most important risk factor leading to second cancers. This risk, determined from cancer registry data which cover entire populations, may be further increased by individual
Figure 25.1 Average annual cancer incidence in the UK by gender and age attained. Diamonds, male; squares, female.
