Haveman J, Jansen W, van der Schueren E, Breur K
Br J Cancer. 1981 Jun;43(6):864-70. doi: 10.1038/bjc.1981.126.
Evidence is presented that microscopic tumours (of a transplantable murine mammary carcinoma, M8013X) grow faster than larger, palpable, tumours. Microscopic tumours are also more radiosensitive than larger tumours. The decrease in radiosensitivity in larger tumours is prevented to a large extent by misonidazole, which has no significant effect on the radiosensitivity of microscopic tumours. The retardation in growth rate which occurs after the fast microscopic growth is probably related to the appearance of hypoxic cells. Both the decrease in growth rate and the progressive development of hypoxia may be caused by the relatively poorer blood flow in larger tumours. Part of the radioresistance in "large" tumours ( approximately 250 mm3) seems to be due to factors other than hypoxia; maybe cell-kinetic factors also play a role. The intrinsic radiosensitivity of tumour cells in microscopic tumours was assessed by means of a modified latency test: the Dq and Do were 2.2 and 2.5 Gy respectively. A number of factors which may influence the reliability of these estimates are discussed.
有证据表明，（可移植性小鼠乳腺癌M8013X的）微小肿瘤比更大的、可触及的肿瘤生长得更快。微小肿瘤对辐射也比大肿瘤更敏感。米索硝唑在很大程度上可防止大肿瘤放射敏感性的降低，而对微小肿瘤的放射敏感性没有显著影响。快速的微小生长之后出现的生长速率减慢可能与缺氧细胞的出现有关。生长速率的降低和缺氧的逐渐发展可能都是由较大肿瘤中相对较差的血流引起的。“大”肿瘤（约250立方毫米）的部分放射抗性似乎是由缺氧以外的因素引起的；也许细胞动力学因素也起作用。通过改良的潜伏期试验评估微小肿瘤中肿瘤细胞的固有放射敏感性：Dq和Do分别为2.2和2.5戈瑞。讨论了一些可能影响这些估计可靠性的因素。
