Mammary tumor occurrence in beagles given 239Pu.
Comparison of 120 young adult female beagles given 0.026 to 106 kBq 239Pu kg-1 by intravenous injection and 63 comparable female control beagles showed that there were no significant differences in the risk of mammary tumor appearance between the two groups. This was the case for benign tumors only, for malignant tumors only, and for both malignant and benign tumors considered together. For malignant tumors the observed number was 73 as compared with 69 expected; for benign tumors, there were 131 observed and 126 expected; for all tumors (separate analysis, not just the addition of malignant plus benign), there were 199 observed and 199 expected. Chi-square analysis indicated that the p values for all these comparisons were > 0.05. There were 45 controls (71.4%) with any tumor vs. 67 dogs (55.8%) given Pu (95% C. I. = 46.9% to 86.2%). No significant differences could be established (Kaplan-Meier analysis) between these two groups for survival age at diagnosis of the first mammary tumor, 11.75 +/- 0.30 y for dogs given Pu vs. 11.90 +/- 0.36 y for controls. We reported previously that differences in mammary cancer occurrence had been identified between this same group of control dogs and 57 female beagles given 226Ra as young adults. The present study appears to support the earlier conclusion that something other than alpha irradiation of the skeleton (both 226Ra and 239Pu deposit in bone) seems to affect the appearance of mammary cancers, since internally deposited 226Ra does appear to induce these malignancies, possibly from initial deposition in mammary tissue of the parent radionuclide or the subsequent concentration in sensitive tissue of its radioactive progeny, 22Rn or isotopes of polonium, lead, and bismuth, which are absent in the case of 239Pu.
Lloyd
R D
RD
Radiobiology Laboratory, University of Utah, Salt Lake City 84112, USA.
Bruenger
F W
FW
Angus
W
W
Taylor
G N
GN
Miller
S C
SC
D000818:Animals; D004285:Dogs; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000209:etiology*; D009381:Neoplasms, Radiation-Induced / Q000209:etiology*; D011005:Plutonium / Q000633:toxicity*; D011883:Radium / Q000633:toxicity
D011005:Plutonium; D011883:Radium