Deaths due to non-cancer disease
|Analyses of the Life Span Study (LSS) mortality data (1950-1997) show a statistically significant dose-response
pattern for death from diseases other than cancer. The excess does not
seem limited to any particular disease. Among the 49,114 LSS survivors
with colon doses of at least 0.005 Gy (DS86), 18,049 non-cancer deaths
occurred (excluding deaths attributed to diseases of the blood). Circulatory
diseases account for nearly 60% of these deaths, with digestive diseases,
including liver diseases, and respiratory diseases accounting for about
15% and 10%, respectively.
Aside from diseases of the blood, the number of excess non-cancer deaths
associated with A-bomb exposure is estimated at 150 to 300 cases. The death
rate following exposure to 0.2 Gy (the mean radiation dose for the 49,114
survivors with doses >0.005 Gy) is increased by about 3% over normal
rates. This is less than the death rate increase for solid cancers, where
corresponding increases are 7% in men and 12% in women (age 30 ATB). The
dose-response pattern is still quite uncertain (Figure 1).
. Non-cancer dose-response function for the period 1968-1997 (DS86). The
line indicates the fitted linear ERR model without any effect modification
by age at exposure,
sex or attained age. The points are dose category-specific ERR estimates,
curve is a smoothed estimate derived from the points, and the dashed lines
indicate upper and lower one-standard-error bounds on the smoothed
estimate. The right panel shows the low-dose portion of the
dose-response function in more detail.
|A significant radiation dose-response pattern was also seen for non-cancer
blood diseases. Such diseases were studied separately since they may represent
various hematologic malignant or premalignant conditions. Among the 128
deaths for which medical records were available and in which hematologic
reviews were performed, about 45% were clearly classified as non-neoplastic
blood diseases, 6% were diagnosed as leukemia or other hematopoietic cancers,
and the remainder were potentially preneoplastic.
In the absence of known biological mechanisms, it is important to consider
whether these results might be due to biases or to diagnostic misclassification
of cancer deaths. Investigations have suggested that neither of these factors
can fully explain the findings, especially for circulatory diseases that
have been investigated more fully.
The Adult Health Study (AHS) incidence studies of non-cancer diseases show relationships with
A-bomb dose for benign uterine tumors, thyroid disease (e.g., thyroid nodules),
chronic liver disease, cataract, and hypertension (Figure 2). The LSS mortality
data also show dose-related excesses for respiratory diseases, stroke,
and heart diseases (Figure 3).
Figure 2. Relative risk for AHS incidence of non-cancer diseases at 1-Gy exposure
Figure 3. Excess risk of mortality in the LSS due to non-cancer diseases. The increase
statistically significant for all non-cancer diseases, or specifically
stroke, respiratory diseases, and digestive diseases. The horizontal bars
indicate 90% confidence intervals.
|Although the LSS data on heart disease mortality suggest that radiation
is associated mainly with hypertensive and congestive heart disease, AHS
data also suggest an association with myocardial infarction, as well as
with a measure of atherosclerosis (aortic arch calcification). There is
particular evidence, therefore, from both AHS clinical data and LSS mortality
studies, that the rates of cardiovascular disease are increased in A-bomb
survivors, especially, it appears, for persons exposed at young ages. Studies
regarding possible underlying biological mechanisms are being conducted.
|References about this subject
||Preston DL, Shimizu Y, et al.: Studies of mortality of atomic bomb survivors. Report 13. Solid cancer and noncancer disease mortality: 1950-1997. Radiation Research 2003; 160:381-407
||Yamada M, Wong FL, et al.: Noncancer disease incidence in atomic bombs survivors, 1958-1998. Radiation Research 2004; 161:622-32