Patterns of involvement with malignant lymphoma and implications for treatment decision making.

Decision making in cancer therapy has traditionally evolved through careful observation of the clinical course subsequent to various treatment approaches. This method has also served to delineate the wide spectrum of primary manifestations and patterns of biological behaviour characterizing the malignant lymphomata. Marked disparity has been consistently appreciated between the natural history of lymphomata originating in lymph nodes in contrast to those primary in extranodal sites. The former are usually anatomically generalized at diagnosis whereas primary extranodal lymphomata are commonly localized and more closely resemble carcinomata of the respective organs with their propensity for both regional lymphatic extension and haematogenous spread. Prospective staging of 100 consecutive patients with previously untreated malignant lymphoma has been consistent with this past experience in demonstrating the presence of disseminated involvement in the majority of patients. It has also become apparent that reliance upon either clinical or surgical staging of disease extent is often misleading since widespread disease frequently develops even in those patients staged as having localized involvement and thereby treated with local irradiation. High dose, wide field lymphatic irradiation "á la Hodgkin's disease" seldom constitutes appropriate treatment for patients having lymph node presentations of lymphoma. There is rather a need to recognize the importance of systemic treatment for most cases, negating the utility of routine exhaustive staging since treatment decisions can be based upon readily assessed clinicohistological determinants in the majority of cases.