Lymphoblastoma

In this paper an attempt will be made to evaluate the differences in radiosensitivity of the various types of lymphoblastoma, and a plan will be presented for distinguishing between the types by means of a quantitative therapeutic test with x-ray irradiation, when a mass presents itself in the mediastinum or abdomen and no lymph node is available for biopsy. Tissue Sensitivity in General It is a well established fact that different tissues respond with different degrees of sensitivity to irradiation. Bergonié and Tribondeau established the axiom that cells are most sensitive in their embryonic state. Normal cells that are less differentiated respond more quickly than those that are adult in type. This apparently depends on the presumption that less differentiated cells have a greater power of reproduction and the fact that cells are most sensitive to irradiation during their mitotic stage. The response of neoplastic tissues to irradiation is governed by the same factors. Since neoplastic tissues are rapidly growing, they show a high degree of mitotic activity and hence are more sensitive to irradiation. Other influences, however, come into play. As Kaplan (6) has pointed out, the response of neoplastic tissue to irradiation depends, also, on (a) the condition of the patient, (b) the position and situation of the lesion, (c) the extent of invasion, and (d) the bed of the tumor, its nutritional supply and vascular system, all of which are essential to tumor growth. Most observers agree that the lymphocyte and its predecessor, the lymphoblast, are the most sensitive cells in the body. It should be recalled, moreover, that the adult lymphocyte is the end product of a series of more immature cells comprising the lymphocytic series. It would be logical to assume that the more immature cells of the group, the lymphoblasts and prolymphocytes, would be most sensitive. Bearing in mind these general remarks, the individual radiosensitivity of lymphoblastomas will be classified and discussed. Types of Lymphoblastoma and their Relative Radiosensitivity The lymphoblastomas may be classified as follows: 1. Giant follicular lymphadenopathy. 2. Lymphatic leukemia. 3. Lymphosarcoma. 4. Polymorphous-cell sarcoma. 5. Hodgkin's disease. 1. Giant Follicular Lymphadenopathy: While giant follicular lymphadenopathy is not essentially a malignant lymphoblastoma, it has been included in this group because, according to an estimate by Symmers (11), as many as 20 per cent of the cases may undergo transformation into polymorphous-cell sarcoma, Hodgkin's disease, or leukemia. Rubenfeld (10) has demonstrated the extreme radiosensitivity of this condition, effecting not only control but probably cure with individual x-ray doses of 100 to 150 r to the involved lymph nodes or spleen, and total doses ranging from 300 to 1,200 r measured in air. The factors he used were 200 kv., 10 to 20 ma., 0.5 mm. Cu + 1.0 mm. A1, at distances of 40 to 50 cm.