<b>New Cancers</b> 

Ionizing radiations have been shown to be carcinogenic to man, even in low dosage. High radiation dosage and severe radiation damage are not essential for radiation-associated New Cancers. After irradiation for malignancy, the latent period for New Cancer induction varied from 5 years to 31 years in one study, peak frequency was between 5 and 10 years in another. All these cases showed no evidence of recurrence or metastases of the original primary lesion. Another group of people receiving irradiation for a noncancerous condition also had an increase of cancer deaths. Cancer mortality remained high for up to 50 years for this group. The risk of a second cancer from radiation damage may persist to the end of life.

Areas that have been irradiated should be regularly observed not only for recurrence of the initial tumor, and other late effects of irradiation, but also the possibility of later development of a New Cancer. And for New Cancers, the necessity of systematically searching for previous irradiations in the affected zone is emphasized.

Death from cancer, in relation to radiation dose, was evaluated among 4153 women treated with intrauterine radium (226Ra) capsules for <b>benign</b> gynecologic bleeding disorders between 1925 and 1965. <b>Deaths due to cancer in this group were increased, especially cancers of organs close to the radiation source</b>.
 
For organs receiving greater than <b>5 Gy: excess mortality of 100 to 110% was noted for cancers of the uterus and bladder</b> 10 or more years following irradiation.

Among cancers of organs receiving average or local doses of <b>1 to 4 Gy: excesses of 30 to 100% were found for leukemia and cancers of the colon and genital organs other than uterus</b>.
 
Among organs typically receiving <b>0.1 to 0.3 Gy: a 30% excess was noted for kidney cancer</b> (based on eight deaths), and there was a <b>60% excess of pancreatic cancer</b> among 10-year survivors, but little evidence of dose-response.

Estimates of the excess relative risk per Gray were 0.006 for uterus, 0.4 for other genital organs, 0.5 for colon, 0.2 for bladder, and <b>1.9 for leukemia</b> [see myelodysplasia].

For organs receiving greater than <b>1 Gy: cancer mortality remained elevated for more than 30 years</b>, supporting the notion that radiation damage persists for many years after exposure. 
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Post irradiation sarcoma of soft tissue and bone is a well-known occurrence. It occurs in the irradiated area. The five-year survival for this is about 30%, and follows the usual sarcoma pattern, with size and grade of tumor and successful surgical excision being important determinants. 

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