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Biomedical subjects

S Hellman

Publications and source records attributed to S Hellman.

At least 181 records · Page 10Linked to original sources
PubMed1978

Proliferative capacity of murine hematopoietic stem cells.

The present study demonstrates a decrease in self-renewal capacity with serial transfer of murine hematopoietic stem cells. Production of differentiated cell progeny is maintained longer than stem cell self-renewal. In normal animals the capacity for self-renewal is not decreased with increasing donor age. The stem cell compartment in normal animals, both young and old, appears to be proliferative quiescent. After apparent recovery from the alkylating agent busulfan, the probability of stem cell self-renewal is decreased, there is a permanent defect in the capacity of the bone marrow for serial transplantation, and the stem cells are proliferatively active. These findings support a model of the hematopoietic stem cell compartment as a continuum of cells with decreasing capacities for self-renewal, increasing likelihood for differentiation, and increasing proliferative activity. Cell progress in the continuum in one direction and such progression is not reversible.

Animals↗
PubMed1978

Computer-controlled radiation therapy.

Radiation therapy is often hampered in important body regions by the need to transit sensitive normal tissues which act as dose-limiting barriers. Computer-controlled radiation therapy permits the simultaneous variation of multiple treatment parameters during irradiation of the patient, producing improved dose distributions with the potential for improved local control. Equipment used for this purpose includes a Mevatron XII linear accelerator, redesigned for automatic control, and a PDP 11/45 minicomputer. Dose distributions are shown and potential clinical gains discussed.

Computers↗
PubMed1978

Results of treating stage I and II carcinoma of the breast with primary radiation therapy.

Eighty patients with stage I and II carcinoma of the breast were treated with primary radiation therapy between July 1968 and December 1975 at the Joint Center for Radiation Therapy. The median followup time was 41 months. Only one local recurrence was observed. The survival at 5 years was 88% for stage I and 72% for stage II. The relapse-free survival at 5 years was 91% for stage I and 56% for stage II. Of breasts evaluated for cosmetic results, 66% were judged good or excellent by physicians and 81% were judged good or excellent by patients. One patient developed a pericardial reaction related to treatment which required hospitalization. Other complications were mild and cleared without additional therapy.

Adult↗
PubMed1978

Effect of primary treatment modality on the metastatic pattern of mammary carcinoma.

In animal tumor systems, all three major treatment modalities, surgery, radiotherapy, and chemotherapy, may increase the incidence of metastases in the presence of circulating viable tumor cells. In breast cancer patients, selected studies can be found which report an increased incidence of metastases after surgery, radiotherapy, or chemotherapy, but these effects appear to exert little influence on overall survival. Caution is advised in using systemic therapy prior to effective primary tumor cytoreductive treatment. Clinical trials in advanced local disease should be done to test this concern. Minimal surgery, loco-regional radiotherapy, and effective adjuvant systemic therapy may result in the improved survival of patients with breast cancer with minimal functional or cosmetic impairment.

Antineoplastic Agents↗
PubMed1978

Proliferation kinetics of a human breast cancer line in vitro following treatment with 17beta-estradiol and 1-beta-D-arabinofuranosylcytosine.

The effect of 17beta-estradiol on an estrogen receptor-positive human breast cancer cell line (MCF-7) was studied. Low concentrations (10(-9) M) of 17beta-estradiol enhanced the rate of cell proliferation; the overall cell cycle time was shortened; and the proportion of cells in the S phase increased. Higher concentrations (10(-7) M) suppressed proliferation and slightly decreased the proportion of the cells in DNA synthesis. When combined with 1-beta-D-arabinofuranosylcytosine, an S-phase-specific chemotherapeutic agent, 10(-9) M 17beta-estradiol enhanced cell killing. This enhancement was not observed with 10(-7) M 17beta-estradiol. Kinetic changes caused by hormones have profound implications in clinical therapy, since the efficacy of cycle active agents may be altered.

Breast Neoplasms↗
PubMed1977

The place of radiation therapy in the treatment of non-Hodgkin's lymphomas.

The use of Hodgkin's disease as a model for the evaluation and management of the non-Hodgkin's lymphomas may not be appropriate. This latter group of different syndromes and diseases differs significantly in their clinical presentation from each other as well as from Hodgkin's disease. Survival must be separated from relapse-free survival since the latter is a measure of the effectiveness of any individual therapy being applied. Localized nodal lymphoma is uncommon, but important to identify since it is potentially curable by irradiation. Stage I nodular, non-histiocytic lymphomas treated by radiation results in significant, extended, relapse-free survival. All other localized nodal lymphoma is associated with a high proportion of patients relapsing outside the treatment portal. Whole body irradiation is a useful systemic agent causing regression for an extended period of time in stage III or stage IV nodular lymphoma. Chemotherapy seems to have a limited value in nodular lymphomas, with no clear evidence that combination chemotherapy is more effective than single agents. In diffuse lymphomas, aggressive chemotherapy shows more promise, with diffuse histiocytic lymphoma having extended relapse-free survival.

Bleomycin↗
PubMed1977

Radiation therapy as initial treatment for early stage cancer of the breast without mastectomy.

This report describes 150 patients with clinical stage I and II carcinoma of the breast treated at four institutions--Yale University School of Medicine, Harvard Medical School-Joint Center for Radiation Therapy, Hahnemann Medical College, Jefferson Medical College--with radiotherapy only following excisional biopsy. Closely similar treatment policies were followed at all four centers, 4500-5000 rads minimum tumor dose being delivered to the entire breast and axillary, supraclavicular and internal mammary nodes. Forty-six of 49 stage I patients treated are alive without disease, the actuarial relapse-free survival being 91% at 5 years. Of the 101 stage II patients, 75 are alive without disease with a relapse-free actuarial survival of 60% at 5 years. Local failure has occurred in 10 patients (9 stage II and 1 stage I, 6.6%) 5 of whom are disease-free following mastectomy. The results obtained in this study are comparable to those of conventional surgery. It is our conclusion that mastectomy is not a necessary part of the treatment of small breast cancers, that radiation without mastectomy is an acceptable alternative with far superior cosmetic and functional results. Adjuvant chemotherapy should be considered particularly in stage II patients in view of their 40% relapse rate.

Antineoplastic Agents↗
PubMed1977

Treatment of carcinoma of the breast by radiation therapy.

One hundred and fifty patients with carcinoma of the breast were treated by radiation therapy without mastectomy. Seventy-seven patients had excisional biopsy of the breast mass while the remainder had incisional biopsy or needle biopsy. There has been 100% local control in patients with Stage I or Stage II disease. The local control rate in Stage III is 67.5%. Those patients who had excisional biopsy had a significantly lower incidence of local recurrence than did those in whom the tumor was left in situ. The cumulative survival probability at five years is 100% for Stage I, 65% for Stage II and 26% for Stage III. Recommendations are made concerning axillary node sampling and adjuvant chemotherapy for patients treated by this technique.

Brachial Plexus↗
PubMed1977

Stages IIB and IIIB Hodgkin's disease. Results of combined modality treatment.

Between April 1969, and December 1974, 23 IIB and 26 IIIB surgically staged patients with Hodgkin's disease were treated at the Joint Center for Radiation Therapy. Stage IIB patients received either mantle and para-aortic-splenic pedicle, or total modal irradiation (TNI) alone or with the addition of combination chemotherapy. Relapse-free survival is 83% and overall survival 88%. Eleven patients received combination chemotherapy in addition to mantle and para-aortic irradiation, and both the relapse-free and overall survival are 100%. Of the stage IIIB patients, seven received TNI alone with four relapses, and 19 were treated with TNI and MOPP with two relapses. These relapse rates are significantly different (p less than 0.05). The relapse-free and overall survival for all stage IIIB patients is 66% and 84% respectively. These data imply that irradiation alone is not adequate treatment for stage IIIB Hodgkin's disease, and that with the addition of combination chemotherapy both the disease-free and overall survival is similar to that of early stage Hodgkin's disease without systemic symptoms. The ideal management of stage IIB Hodgkin's disease is less certain; it is our plan to study the efficacy of combined modality treatment.

Adolescent↗
PubMed1977

Hematopoietic stem cells: effect of preirradiation, bleeding, and erythropoietin on thrombopoietic differentiation.

A method of measuring differentiation of stem cells towards platelets is described using syngeneic bone marrow injected into lethally irradiated mice. Fourteen days after such injection, the platelet counts are found to be proportional to the number of bone marrow cells injected and can be used as a measure of platelet progenitors. Perturbation of the milieu in which the transplanted marrow is placed by host preirradiation, bleeding, or erythropoietin administration leads to enhanced thrombopoiesis. It has been shown previously that similar perturbation favors erythropoiesis at the expense of granulopoiesis. The data from these and other experiments appear to be consistent, with a model of the stem cell compartment as a continuum with proliferative activity increasing as commitment is restricted. These functions vary inversely with the capacity for self-renewal. The various stem cell assays measure different ranges of stem cells, but overlap within this continuum.

Animals↗
PubMed1977

Total-body irradiation in the treatment of lymphocytic lymphoma.

Seventy-eight patients with advanced lymphocytic lymphoma have been treated by total-body irradiation (TBI) since 1969. Fifty-one of these patients received TBI as their initial and only primary therapy, and of these, 36 had a nodular histology and 15 had a diffuse histology according to the Rappaport classification. Treatment consisted of 15 rads twice weekly to 150 rads total dose. Persistent local tumors were given local boost irradiation. None of these 78 patients experenced significant morbidity; toxicity was confined to thrombocytopenia, and in 40% of the patients treatment was administered over a prolonged course to allow platelet recovery. Of the 51 patients who received TBI as primary treatment, 80% achieved a complete response for a median relapse-free survival of 24 months and an actuarial 5-year survival of 68%. TBI is an effective therapy in advanced lymphocytic lymphoma and produces long remissions without maintenance in many patients. It should be considered a systemic agent, and its use in combination with chemotherapeutic agents deserves further investigation.

Blood Platelets↗
PubMed1976

The role of postoperative irradiation in carcinoma of the breast.

Chest wall and regional nodal recurrences, and survival following postmastectomy radiation therapy, were analyzed in 352 patients. Patients with T1 and T2 central and medial breast lesions, negative axillary nodal findings, and no evidence of skin or chest wall extension received irradiation to the peripheral lymphatics alone. There were no chest wall recurrences among these patients. The remainder of the patients, including those with axillary nodal involvement, regardless of the site of the primary breast lesion received irradiation by a three-field technique directed to both chest wall and regional nodes. The chest wall recurrence rate was 1.9% when axillary nodes were negative for metastatic disease, 1.3% when the axillary nodes showed less than 50% positivity, and 14.2% when axillary nodes showed greater than 50% involvement. The overall chest wall recurrence rate was 5.1%. A possible mechanism of chest wall recurrence is discussed. Cumulative 5-year survival for stage I is 76%, for stage II, 79%, and for stage III, 57%. If chemotherapy proves to be effective in controlling distant microscopic disease local control may become an equally critical issue in long-term survival of patients with breast carcinoma.

Axilla↗