Patricia Prior

Leukemia Following Hodgkin's Disease

To investigate the effect of different treatments for Hodgkins disease on the risk of leukemia, we used an international collaborative group of cancer registries and hospitals to perform a case-control study of 163 cases of leukemia following treatment for Hodgkins disease. For each case patient with leukemia, three matched controls were chosen who had been treated for Hodgkins disease but in whom leukemia did not develop. The use of chemotherapy alone to treat Hodgkins disease was associated with a relative risk of leukemia of 9.0 (95 percent confidence interval, 4.1 to 20) as compared with the use of radiotherapy alone. Patients treated with both had a relative risk of 7.7 (95 percent confidence interval, 3.9 to 15). After treatment with more than six cycles of combinations including procarbazine and mechlorethamine, the risk of leukemia was 14-fold higher than after radiotherapy alone. The use of radiotherapy in combination with chemotherapy did not increase the risk of leukemia above that produced by the use of chemotherapy alone, but there was a dose-related increase in the risk of leukemia in patients who received radiotherapy alone. The peak in the risk of leukemia came about five years after chemotherapy began, and a large excess persisted for at least eight years after it ended. After adjusting for drug regimen, we found that patients who had undergone splenectomy had at least double the risk of leukemia of patients who had not, and an advanced stage of Hodgkins disease carried a somewhat higher risk of leukemia than Stage I disease. We conclude that chemotherapy for Hodgkins disease greatly increases the risk of leukemia and that this increased risk appears to be dose-related and unaffected by concomitant radiotherapy. In addition, the risk is greater for patients with more advanced stages of Hodgkins disease and for those who undergo splenectomy.

Radiation dose and second cancer risk in patients treated for cancer of the cervix

The risk of cancer associated with a broad range of organ doses was estimated in an international study of women with cervical cancer. Among 150,000 patients reported to one of 19 population-based cancer registries or treated in any of 20 oncology clinics, 4188 women with second cancers and 6880 matched controls were selected for detailed study. Radiation doses for selected organs were reconstructed for each patient on the basis of her original radiotherapy records. Very high doses, on the order of several hundred gray, were found to increase the risk of cancers of the bladder [relative risk (RR) = 4.0], rectum (RR = 1.8), vagina (RR = 2.7), and possibly bone (RR = 1.3), uterine corpus (RR = 1.3), cecum (RR = 1.5), and non-Hodgkins lymphoma (RR = 2.5). For all female genital cancers taken together, a sharp dose-response gradient was observed, reaching fivefold for doses more than 150 Gy. Several gray increased the risk of stomach cancer (RR = 2.1) and leukemia (RR = 2.0). Although cancer of the pancreas was elevated, there was no evidence of a dose-dependent risk. Cancer of the kidney was significantly increased among 15-year survivors. A nonsignificant twofold risk of radiogenic thyroid cancer was observed following an average dose of only 0.11 Gy. Breast cancer was not increased overall, despite an average dose of 0.31 Gy and 953 cases available for evaluation (RR = 0.9); there was, however, a weak suggestion of a dose response among women whose ovaries had been surgically removed. Doses greater than 6 Gy to the ovaries reduced breast cancer risk by 44%. A significant deficit of ovarian cancer was observed within 5 years of radiotherapy; in contrast, a dose response was suggested among 10-year survivors. Radiation was not found to increase the overall risk of cancers of the small intestine, colon, ovary, vulva, connective tissue, breast, Hodgkins disease, multiple myeloma, or chronic lymphocytic leukemia. For most cancers associated with radiation, risks were highest among long-term survivors and appeared concentrated among women irradiated at relatively younger ages.

Leukemia Following Chemotherapy for Ovarian Cancer

An international collaborative group of cancer registries and hospitals identified 114 cases of leukemia following ovarian cancer. We investigated the possible etiologic role of chemotherapy, radiotherapy, and other factors, using a case-control study design, with three controls matched to each case of leukemia. Chemotherapy alone was associated with a relative risk of 12 (95 percent confidence interval, 4.4 to 32), as compared with surgery alone, and patients treated with both chemotherapy and radiotherapy had a relative risk of 10 (95 percent confidence interval, 3.4 to 28). Radiotherapy alone did not produce a significant increase in risk as compared with surgery alone. The risk of leukemia was greatest four or five years after chemotherapy began, and the risk was elevated for at least eight years after the cessation of chemotherapy. The drugs cyclophosphamide, chlorambucil, melphalan, thiotepa, and treosulfan were independently associated with significantly increased risks of leukemia, as was the combination of doxorubicin hydrochloride and cisplatin. Chlorambucil and melphalan were the most leukemogenic drugs, followed by thiotepa; cyclophosphamide and treosulfan were the weakest leukemogens, and the effect per gram was substantially lower at high doses than at lower doses. The extent to which the relative risks of leukemia are offset by differences in chemotherapeutic effectiveness is not known.

Cancer and rheumatoid arthritis: Epidemiologic considerations

Statistical methods used to investigate the epidemiology of cancer in rheumatoid arthritis are reviewed and their relative merits discussed. A cohort analysis of cancer morbidity was carried out on a consecutive series of 489 patients with rheumatoid arthritis seen at the Queen Elizabeth Medical Centre, Birmingham, United Kingdom between 1964 and 1978 and followed to December 31, 1983. Forty-two cancers were observed in the series in comparison with 31.13 expected (p less than 0.05) on the basis of cancer morbidity rates for the West Midlands region. The excess was due to the high relative risk of cancers of lymphatic and hematopoietic tissues (observed = 11, expected = 1.27, relative risk = 8.7, p less than 0.001). The effects of confounding factors, including duration of rheumatoid arthritis and hospital selection on the level and pattern of risk over time were examined. When two cases diagnosed soon after first attendance at hospital were excluded, lymphomas (ICD 200, 201, 8th Revision) showed a pattern of increasing relative risk with time from five years after first attendance. The increasing risk appears to be unrelated to the use of immunosuppressive or cytotoxic drugs.

MORTALITY IN CROHN'S DISEASE

A series of 513 patients with Crohns disease, who were followed for 1 to more than 35 yr by one unit, experienced a twofold increased risk of dying compared with a matched group drawn from the general population (102 observed; 51.8 expected; p < 0.001). The overall risk was similar for men and women and was greatest in the younger patients within a few years of diagnosis. The relative risk of dying decreased as the age at diagnosis of their Crohns disease increased and also fell as the period of time from diagnosis increased. There was a small but significant excess of death from tumors of the digestive organs (9 observed; 4 expected; p < 0.05). There was also a significant excess of deaths from suicide in women (3 observed; 0.4 expected; p < 0.01). The major burden of mortality lay in causes directly attributable to Crohns disease or to associated complications within the digestive system (46 observed; 1.41 expected; p < 0.001).

Leukemia following chemotherapy for ovarian cancer

An international collaborative group of cancer registries and hospitals identified 114 cases of leukemia following ovarian cancer. We investigated the possible etiologic role of chemotherapy, radiotherapy, and other factors, using a case-control study design, with three controls matched to each case of leukemia. Chemotherapy alone was associated with a relative risk of 12 (95 percent confidence interval, 4.4 to 32), as compared with surgery alone, and patients treated with both chemotherapy and radiotherapy had a relative risk of 10 (95 percent confidence interval, 3.4 to 28). Radiotherapy alone did not produce a significant increase in risk as compared with surgery alone. The risk of leukemia was greatest four or five years after chemotherapy began, and the risk was elevated for at least eight years after the cessation of chemotherapy. The drugs cyclophosphamide, chlorambucil, melphalan, thiotepa, and treosulfan were independently associated with significantly increased risks of leukemia, as was the combination of doxorubicin hydrochloride and cisplatin. Chlorambucil and melphalan were the most leukemogenic drugs, followed by thiotepa; cyclophosphamide and treosulfan were the weakest leukemogens, and the effect per gram was substantially lower at high doses than at lower doses. The extent to which the relative risks of leukemia are offset by differences in chemotherapeutic effectiveness is not known.