Lymphomas: Relationship Between Dosage and Recurrence

Abstract

The treatment of lymphoma has, over the past half century, steadily improved, and survival rates have risen. The authors believe that this is due primarily to better radiotherapy. The advent of high-energy radiation, either from high-voltage generators or isotopes, i.e., cobalt 60 and cesium 137, has made possible higher dose irradiation to demonstrable or palpable lesions. The purpose of this paper is to explore the relationship between the quantity of radiation delivered to localized areas and the recurrences in those fields. The publications in 1958 of Peters and Middlemiss (8) gave encouragement to therapists whose observations indicated inadequate control by low dosage patterns. In the early part of this century, it was customary to employ 1,000 r or less to separate areas. Some regressions did result; however, many recurrences were noted after such limited quantities of irradiation. Peters and Middlemiss, as well as Kaplan (11, 13) have lucidly described the rationale for irradiating not only the involved areas, but contiguous fields as well. We were aware in 1953, when our program began, that 2,000 rad to anygiven field often failed to control disease. At that time only conventional radiation therapy was available, which limited our ability to deliver much over 2,000 rad to a particular site of involvement. In June 1955, cobalt teletherapy became accessible and from that time on dosage was increased to 2,500, to 3,000, and eventually to 3,500 rad to any field treated. Our experience parallels that of many other centers treating lymphoma. During the past decade, chemotherapy has played a large role in the treatment of lymphoma. The values and the limitations of such therapy are by now fairly well established. It has been our experience that radiation has proved the treatment of choice for lymphomas which remain localized to one or two areas. Chemotherapy is at this time the preferred modality for widely disseminated forms of the disease. It should be noted that large localized masses existing concomitantly with systemic forms of lymphomas frequently fail to respond to chemotherapy and require, in addition, localized radiotherapy. The records of 185 patients (103 males and 82 females) with a diagnosis of lymphoma, who underwent treatment by irradiation between 1953 and the present were reviewed, and 34 five-year survivals were found, a rate of 18.5 per cent. An 18.5 per cent survival rate is distressingly low, but it should be noted that a number of the patients included in this series had received localized irradiation for large masses and were suffering from widely disseminated forms of the disease. The diagnosis of lymphoma, as established by the “pathologist,” frequently carries detailed and equivocal descriptions. For the sake of simplicity, we have classified our cases as follows: The five-year survival data as related to the pathological grouping were: