nearly all sites other than breast, ovary, and thyroid, risks are higher for males than females, with especially large differences for cancers of the liver and bladder. In males, prostate cancer accounts for more than a third of the incident cases. In females, breast cancer accounts for about a third of the incident cases.

Tables 12-5A and 12-5B show estimates of the LAR for a population with an age composition similar to that of the U.S. population exposed to 0.1 Gy. Estimates of cancer incidence (Table 12-5A) and mortality (Table 12-5B) are shown for several site-specific solid cancers. The committee’s preferred estimates are those in the third and sixth columns. These were obtained by calculating a weighted mean (on a logarithmic scale) of linear estimates based on relative and absolute risk transport (also shown) and then reducing them by DDREF of 1.5 as described earlier. The subjective confidence intervals reflect uncertainty due to sampling variability, transport, and DDREF. For most sites, these intervals cover at least an order of magnitude. For many sites, statistical uncertainty alone is large (see Table 12-2). For cancers of the stomach, liver, lung (females), prostate, and uterus, estimates based on relative and absolute risk differ by a factor of 2 or more, contributing substantially to the uncertainty in estimates for these sites. It is perhaps surprising that the LAR for lung cancer is nearly twice as high for females as males even though the baseline risks show a reverse pattern. It is possible that this and other patterns for site-specific cancers reflect statistical anomalies or other biases in LARs estimated with high uncertainty.

The committee’s preferred estimates for risk of all solid cancers can be obtained as the sums of the site-specific estimates and are shown in the next-to-the-last line of Tables 12-5A and 12-5B. These estimates are higher for females than males, even though the reverse is true for baseline risks (Table 12-4), a finding that comes about primarily because of the contribution of breast cancer and lung cancer (as noted above). For cancer mortality, the years of life lost per death are also of interest. For the sum of sites estimates, this was 14 per death for males and 15 per death for females.

The LAR for all cancer incidence is about twice that for cancer mortality. However, this ratio varies greatly by cancer site. The largest contribution to cancer incidence in males is from the residual category of “other solid cancers” followed by colon and lung cancer. These three categories are also the most important contributors to cancer mortality. Cancers of the lung, and breast and other solid cancers con-

TABLE 12-5A Lifetime Attributable Risk of Solid Cancer Incidence

Cancer Site

Males

Females

LAR Based on Relative Risk Transporta

LAR Based on Absolute Risk Transportb

Combined and Adjusted by DDREFc (Subjective 95% CId)

LAR Based on Relative Risk Transporta

LAR Based on Absolute Risk Transportb

Combined and Adjusted by DDREFc (Subjective 95% CId)

Incidence

Stomach

25

280

34 (3, 350)

32

330

43 (5, 390)

Colon

260

180

160 (66, 360)

160

110

96 (34, 270)

Liver

23

150

27 (4, 180)

9

85

12 (1, 130)

Lung

250

190

140 (50, 380)

740

370

300 (120, 780)

Breast

 

510 Not used

460

310 (160, 610)

Prostate

190

6

44 (<0, 1860)

 

Uterus

 

19

81

20 (<0, 131)

Ovary

66

47

40 (9, 170)

Bladder

160

120

98 (29, 330)

160

100

94 (30, 290)

Other

470

350

290 (120, 680)

490

320

290 (120, 680)

Thyroid

32

No model

21 (5, 90)

160

No model

100 (25, 440)

Sum of site-specific estimates

1400

1310e

800

2310f

2060e

1310

All solid cancer modelg

1550

1250

970 (490, 1920)

2230

1880

1410 (740, 2690)

NOTE: Number of cases per 100,000 persons of mixed ages exposed to 0.1 Gy.

aLinear estimate based on ERR models shown in Table 12-2 with no DDREF adjustment.

bLinear estimate based on EAR models shown in Table 12-2 with no DDREF adjustment.

cEstimates obtained as a weighted average (on a logarithmic scale) of estimates based on relative and absolute risk transport. For sites other than lung, breast, and thyroid, relative risk transport was given a weight of 0.7 and absolute risk transport was given a weight of 0.3. These weights were reversed for lung cancer. Models for breast and thyroid cancer were based on data that included Caucasian subjects. The resulting estimates were reduced by a DDREF of 1.5.

dIncluding uncertainty from sampling variability, transport, and DDREF. Sampling uncertainty in the parameters that quantify the modifying effects of age at exposure and attained age is not included except for the all solid cancer model.

eIncludes thyroid cancer estimate based on ERR model.

fIncludes breast cancer estimate based on EAR model.

gEstimates based on model developed by analyzing LSS incidence data on all solid cancers excluding thyroid cancer and nonmelanoma skin cancer as a single category. See Table 12-1.



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