Lloyd R D, Bruenger F W, Angus W, Taylor G N, Miller S C
Radiobiology Laboratory, University of Utah, Salt Lake City 84112, USA.
Health Phys. 1995 Sep;69(3):385-90. doi: 10.1097/00004032-199509000-00010.
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.
对120只静脉注射剂量为0.026至106 kBq 239Pu/kg的成年雌性小猎犬与63只具有可比性的雌性对照小猎犬进行比较，结果表明两组之间乳腺肿瘤出现风险无显著差异。无论是仅考虑良性肿瘤、仅考虑恶性肿瘤还是将恶性和良性肿瘤一并考虑，情况均如此。对于恶性肿瘤，观察到的数量为73例，预期数量为69例；对于良性肿瘤，观察到131例，预期126例；对于所有肿瘤（单独分析，而非简单将恶性肿瘤与良性肿瘤相加），观察到199例，预期199例。卡方分析表明，所有这些比较的p值均>0.05。有45只对照犬（71.4%）出现任何肿瘤，而接受钚的犬中有67只（55.8%）出现肿瘤（95%置信区间=46.9%至86.2%）。对于首次诊断出乳腺肿瘤时的存活年龄，接受钚的犬为11.75±0.30岁，对照犬为11.90±0.36岁，两组之间（Kaplan-Meier分析）未发现显著差异。我们之前报道过，在同一组对照犬与57只成年时接受226Ra的雌性小猎犬之间，已发现乳腺癌发生率存在差异。本研究似乎支持了早期结论，即除了骨骼的α辐射（226Ra和239Pu均沉积在骨骼中）之外的其他因素似乎会影响乳腺癌的出现，因为体内沉积的226Ra似乎确实会诱发这些恶性肿瘤，可能是由于母体放射性核素最初沉积在乳腺组织中，或者是其放射性子代22Rn或钋、铅和铋的同位素随后在敏感组织中浓缩，而239Pu的情况并非如此。
