TABLE 6-2 Summary of Risk Estimates for Solid Cancer Incidence by Cancer Site or Organ System

Cancer Site or Organ System

Percentage of Total Casesa

ERR1Sv

EAR per 10,000 PY-Sv

AR,b %

Total solid tumors

100.0

0.63 (0.52, 0.74)c

29.7 (24.7, 34.8)

11.6 (10.2, 14.3)

Oral cavity and pharynx

1.5

0.29 (−0.09, 0.93)

0.23 (−0.08, 0.65)

9.1 (−3.0, 25.9)

Digestive system

55.7

0.38 (0.25, 0.52)

10.4 (7.0, 14.0)

7.8 (5.3, 10.6)

Esophagus

2.1

0.28 (−0.21, 1.0)

0.30 (−0.23, 1.0)

6.5 (−5.0, 22.5)

Stomach

30.9

0.32 (0.16, 0.50)

4.8 (2.5, 7.4)

6.5 (3.5, 10.5)

Colon

5.3

0.72 (0.29, 1.3)

1.8 (0.74, 3.0)

14.2 (5.9, 23.9)

Rectum

4.1

0.21 (−0.17, 0.75)

0.43 (−0.35, 1.5)

4.4 (−3.6, 14.6)

Liver

6.8

0.49 (0.16, 0.92)

1.6 (0.54, 2.9)

10.9 (3.6, 19.4)

Gallbladder

3.4

0.12 (−0.27, 0.72)

0.18 (−0.41, 1.1)

2.2 (−5.1, 13.1)

Pancreas

2.8

0.18 (−0.25, 0.82)

0.24 (−0.36, 1.1)

3.5 (−5.2, 15.3)

Respiratory system

11.9

0.80 (0.50, 1.2)

4.4 (2.9, 6.1)

16.3 (10.6, 22.6)

Trachea, bronchus, and lung

10.1

0.95 (0.60, 1.4)

4.4 (2.9, 6.0)

18.9 (12.5, 26.0)

Nonmelanoma skin

2.0

1.0 (0.41, 1.9)

0.84 (0.40, 1.4)

24.1 (11.5, 38.6)

Female breast

6.1

1.6 (1.1, 2.2)

6.7 (4.9, 8.7)

31.9 (23.2, 41.1)

Uterus

8.4

−0.15 (−0.29, 0.10)

−1.1 (−2.1, 0.68)

−3.3 (−6.4, 2.1)

Ovary

1.5

0.99 (0.12, 2.3)

1.1 (0.15, 2.3)

17.7 (2.4, 37.3)

Prostate

1.6

0.29 (−0.21, 1.2)

0.61 (−0.46, 2.2)

7.0 (−5.3, 25.5)

Urinary organs and kidney

3.8

1.2 (0.62, 2.1)

2.1 (1.1, 3.2)

22.3 (11.8, 34.2)

Urinary bladder

2.4

1.0 (0.27, 2.1)

1.2 (0.34, 2.1)

16.3 (4.8, 30.1)

Kidney

0.8

0.71 (−0.11, 2.2)

0.29 (−0.50, 0.79)

15.2 (−2.6, 41.3)

Nervous system

1.5

0.26 (−0.23, 1.3)

0.19 (−0.17, 0.81)

5.7 (−5.3, 24.5)

Thyroid

2.6

1.2 (0.48, 2.1)

1.6 (0.78, 2.5)

25.9 (12.4, 40.7)

a254 solid cancers of other and ill-defined sites are included in the total solid tumors category.

bAR is the attributable risk, which in this case is the percentage of cases in exposed survivors attributed to radiation exposure.

cValues in parentheses are the 95% confidence limits.

SOURCE: Thompson and others (1994).

occurring in the period 1958–1993 showed a clear decline in the ERR/Sv with either age at exposure or attained age when evaluated separately. The EAR was also found to decrease with age at exposure, but to increase with attained age at least up to age 50. These analyses, as well as earlier analyses by Tokunaga and colleagues (1994) and by Thompson and coworkers (1994), found that the dose-response for breast cancer was well described by a linear function. Tokunaga and colleagues (1994) also report a strong attained age effect, with an ERR/Sv of 13 for breast cancer occurring before age 35 compared to an ERR/Sv of about 2 for breast cancer occurring after age 35.

Land and colleagues (2003) reported on an incidence survey of breast cancers diagnosed during 1950–1990. As in previous analyses a strong linear dose-response was found. A modified isotonic regression approach, which required only that the ERR/Sv be monotonic in age, was used to evaluate in detail the modification of the dose-response by age at exposure and attained age. The abstract notes that “exposure before age 20 was associated with higher ERR1Sv compared to exposure at older ages, with no evidence of consistent variation by exposure age under 20. ERR1Sv was observed to decline with increasing attained age, with by far the largest drop around age 35.”

Thyroid Cancer

Like breast cancer, thyroid cancer risks are described well by a linear dose-response function and also show a strong dependence on age at exposure. In fact, there is little evidence of a dose-response for persons exposed in adulthood (Thompson and others 1994; Ron and others 1995a), while the ERRs/Sv for those exposed as children were large (9.5 for persons exposed under age 10, and 3.0 for those exposed at ages 10–19; Thompson and others 1994). Although several other cohorts provide data on thyroid cancer risks from external radiation exposure in childhood (Ron and others 1995a), the LSS cohort is the only cohort providing much information on thyroid cancer risk from external radiation exposure in adulthood.

Salivary Gland Cancer

Because some types of salivary gland tumors are not readily identified by the conventional disease classification codes used by tumor registries, a special evaluation that included pathology reviews of both benign and malignant salivary gland tumors was undertaken by Land and colleagues (1996). This resulted in an estimated ERR/Sv of 3.5 (95% CI



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