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Biomedical subjects

T R Fears

Publications and source records attributed to T R Fears.

At least 37 records · Page 2Linked to original sources
PubMed1996

Can protocol-specified doses of chemotherapy and radiotherapy be used as a measure of treatment actually received? A CCG/NIH study on long-term survivors of acute lymphocytic leukemia.

In a cohort of 593 long-term survivors of acute lymphocytic leukemia identified through the Children's Cancer Group (CCG), treatment abstracts were obtained and compared to protocol information on radiation therapy and intravenous chemotherapy. This was done in order to evaluate the actual compliance to protocol-specified treatment, and assess if protocol-specified doses can be used in studies of late effects of treatment. The compliance to protocol-specified type of treatment ranged between 95.3% (intrathecal methotrexate) and 98.6% (adriamycin) for chemotherapy, and between 94.1% (cranial radiation) and 97.0% (extended field radiation) for radiation. Concordance with the protocol-specified chemotherapy dose (+/- 25%) was 57.5% for adriamycin, 91.3% for daunomycin, and 48.5% for cyclophosphamide. When concordance was low, most patients received doses that were lower than expected. Concordance with chemotherapy was significantly lower for high-dose regimens than for low-dose regimens. Concordance with protocol-specified radiation dose (+/- 10%) was 87.4% for cranial radiation, 87.8% for spinal radiation, and 85.7% for extended field radiation. Concordance with treatment did not differ by gender, relapse status, or age at diagnosis. In this cohort of leukemia survivors, the validity of type of treatment was greater than the validity of dosage. Great care should be used when drawing conclusions about effects of treatment dosage. Although costly and time consuming, it appears that chart reviews are the most appropriate way to collect information about dose-related effects of therapy.

Adolescent↗
PubMed1996

Experiences of cancer in children and adolescents.

In an effort to understand the effect of cancer diagnosis and treatment in children and adolescents, and to identify issues that should be addressed with newly diagnosed patients, 85 patients with Ewing's sarcoma family tumors (ESFT) were interviewed about their experience of having cancer. This represents 90% of all eligible patients who survived at least 3 years since their diagnosis and who were treated for ESFT at the National Cancer Institute (NCI) from 1965-1993. The mean age of patients at the time of diagnosis was 15.8 +/- 5.3 years, and mean time since diagnosis was 13.6 +/- 6.4 years. Patients from this cohort had a disease usually related to poor outcome. Patients answered five open-ended written questions. Negative experiences that they described included transient and permanent discomfort and disabilities related to cancer; disruption of life or relationships; and emotional aspects of cancer diagnosis or treatment. Positive aspects of having cancer included changed attitudes about self and life, improved relationships with others, or better job performance. Advice for newly diagnosed patients most often dealt with the emotional aspects of cancer. The importance of patient-to-patient support was frequently described. Overall, having cancer was not an entirely negative experience, and it may result in introspection and improved relationships with others.

Adaptation, Psychological↗
PubMed1996

Reproducibility studies and interlaboratory concordance for assays of serum hormone levels: estrone, estradiol, estrone sulfate, and progesterone.

We conducted studies to measure sources of assay variability for estrone, estradiol, estrone sulfate, and progesterone for postmenopausal women (n = 5) and for women in the mid-follicular (n = 5) and mid-luteal (n = 5) phases of the menstrual cycle. A single blood sample from each woman was divided into 2.5-ml aliquots and stored at -70 degrees C, and sets of two aliquots were sent at monthly intervals to each of three laboratories (four for progesterone). Each aliquot was analyzed in duplicate. Thus, within each menstrual category, we were able to estimate the components of variance due to variation among women, variation among aliquots, variation among duplicate measurements, and variation among the 4 analysis days. Using the logarithm of assay measurements, we estimated the percentage of variance attributable to variation among women in each menstrual category, 100 rho, is the estimated intraclass correlation. For each assay, 100 rho exceeded 90% for mid-follicular and mid-luteal women. For postmenopausal women, values of 100 rho exceed 84% for estrone in two laboratories. Values of 100 rho were lower for progesterone in postmenopausal women, although a value of 84% was estimated from one laboratory. These studies indicate that estrogen assays over a period of 3 months permit reliable comparisons among women in a given menstrual category. Progesterone measurements are likewise reliable for women in the mid-follicular and mid-luteal phases but somewhat less satisfactory for postmenopausal women. These assessments of variability pertain only to laboratory techniques and do not allow for secular variation in intra-woman hormone levels. Moreover, although these measurements tend to be reliable enough for making comparisons among women, estimates of coefficients of variation for estrogens are about 10% for mid-follicular and mid-luteal phase women and about 11-20% for postmenopausal women. Coefficients of variation for progesterone are about 10% for mid-luteal, 20% for mid-follicular, and 30% for postmenopausal women.

Analysis of Variance↗
PubMed1995

Survival after retinoblastoma: long-term consequences and family history of cancer.

Retinoblastoma (Rb) is a rare childhood tumor of the eye. In the heritable form, tumors are often bilateral and survivors have a greatly increased risk both for a second malignancy and for having children with Rb. Familial patterns of both cancer and birth defects are poorly understood in families with a heritable cancer, and little is known of the ways that a heritable cancer affects the lives of long-term survivors. To find out more about these and other issues in the lives of long-term survivors of childhood and adolescent cancer, we interviewed 56 adult survivors of retinoblastoma (15 with the heritable form) and 84 brothers and sisters as controls, who formed part of a large retrospective cohort study. Rb survivors were interviewed between 1980 and 1983, when they were 30 years old on average. Types of employment and health problems did not differ between survivors and controls, regardless of sight, but the income of blind survivors was considerably less than that of partially sighted survivors. Despite similar marriage rates, fewer survivors than controls reported a pregnancy (RR = 0.45; 95% CI; 0.24-0.83 for both sexes combined). Parents of children with heritable Rb seemed more likely to have had cancer than parents in families with nonheritable Rb (P = 0.06), and mothers were more likely than fathers to be affected (P = 0.01). This small series suggests that having retinoblastoma may have many long-term consequences, reaching beyond genetic and physical effects to touch family life and income attainment and the health of other family members. Follow-up of more modern cohorts and the use of molecular tools will clarify the long-term consequences of more recent therapies, and patterns of familiar cancer.

Achievement↗
PubMed1995

Melanocytic nevi, dysplastic nevi, and malignant melanoma in children from melanoma-prone families.

BACKGROUND: Melanocytic nevi, particularly dysplastic nevi (DN), are important markers of increased risk of malignant melanoma in adults, but little is known about their prevalence and relation to melanoma in children. OBJECTIVE: Our purpose was to define the prevalence of DN, number of nevi, and their relation to the risk of melanoma in children younger than 20 years of age from melanoma-prone families. METHODS: One hundred twenty-five persons younger than 20 years of age, from 23 melanoma-prone families, underwent clinical evaluation with nevus counts, photography, and biopsy of suspected melanocytic lesions and were observed for development of DN and melanoma. RESULTS: In melanoma-prone families, 37% of children had DN. The patients were divided into four categories: those with melanoma, DN (without melanoma), indeterminant (largely because of age at examination), and unaffected. The risk of melanoma was assessed by nevus number and presence of DN. High nevus number was strongly correlated with the presence of DN. The risk of the development of melanoma in children from melanoma-prone families appeared most related to the presence of DN (relative risk, 45; 95% confidence intervals, 2.6-786.4) and started at an early age. Of note, all children in whom melanoma developed had DN. CONCLUSION: Family history of melanoma and the presence of DN defines children with a high risk for melanoma developing at an early age.

Adolescent↗
PubMed1994

Second malignant tumors after elective end of therapy for a first cancer in childhood: a multicenter study in Italy.

To evaluate the incidence of second malignant tumors in a cohort of subjects previously treated for childhood cancer, we analyzed data from the Off-Therapy Registry (OTR) of the Italian Association of Pediatric Hematology/Oncology, which collects information on children treated for Hodgkin's disease, non-Hodgkin's lymphoma, Wilms' tumor, acute lymphoblastic leukemia (ALL) and acute non-lymphatic leukemia and who had been removed from treatment in the absence of clinical signs of disease, i.e. the off-therapy stage. Second malignant tumors (SMT), diagnosed before December 31, 1988, were identified through a special enquiry to the 36 institutions cooperating in the registry. Observed cases were compared to expected numbers estimated from age- and sex-specific incidence rates derived from the Cancer Registry of the Province of Varese. In a total of 3,310 study subjects, 27 SMTs have been registered. The Cumulative Risk (CR) of SMT was 2.9% 15 years after the end of treatment and the Standard Incidence Ratio (SIR) was 10.8. The ALL sub-cohort had the highest risk of SMT (SIR 13.6) and 9 cases of CNS tumor occurred in this group (SIR 58.9). All 9 had received prophylactic cranial radiotherapy (CRT) and 5 had been treated on one protocol, characterized by low-dose intrathecal methotrexate (IT MTX) given monthly for 2 years after CRT. The Off-Therapy Registry has unique criteria for inclusion; direct comparisons with similar studies are therefore somewhat problematic. However, our data suggest that the risk of SMT in childhood ALL cancer survivors may be greater than previously reported, and that CNS tumors are the most common SMT in this group. The administration schedule of IT MTX may be an important risk factor.

Adolescent↗
PubMed1994

Educational attainment in long-term survivors of childhood acute lymphoblastic leukemia.

OBJECTIVE: To determine the impact of treatment on scholastic performance in the first cohort of survivors of childhood acute lymphoblastic leukemia who are old enough to have completed their educational experience. DESIGN: Retrospective cohort study. SETTING: Twenty-three institutions in the Childrens Cancer Group. SUBJECTS: A total of 593 adult survivors of childhood acute lymphoblastic leukemia and 409 sibling controls. OUTCOME MEASURES: Enrollment in special programs, grades during high school, graduation from high school, college admission, and college graduation. RESULTS: After diagnosis, survivors were more likely than their sibling controls to enter a special education (relative risk [RR] = 3.4; P < .01) or a learning disabled (RR = 3.6; P < .01) program, while just as likely to enter gifted and talented programs (RR = 1.0). The risk associated with special education and learning disabled programs increased with increasing dose of cranial radiotherapy. Despite these problems, survivors generally had the same probability as their siblings of finishing high school, entering college, and earning a bachelor's degree. However, survivors treated with 24 Gy and those diagnosed before 6 years of age were less likely to enter college (RR = 0.67 and 0.6, respectively; P < .01). CONCLUSIONS: This large study demonstrates that childhood acute lymphoblastic leukemia survivors have a greater likelihood of being placed in special education or learning disabled programs than their siblings, but that most are able to overcome these problems. Dose of cranial radiotherapy and age at diagnosis are the most important education-related risk factors.

Adolescent↗
PubMed1994

Death during adulthood in survivors of childhood and adolescent cancer.

BACKGROUND: Therapeutic advances have extended survival for most children and adolescents with cancer beyond 5 years from diagnosis. However, excess mortality continues beyond 5 years, and a significant portion results from causes other than the primary cancer. Risk factors for these deaths are not currently known. Thus, the authors studied mortality in a cohort of adult survivors of childhood and adolescent cancer to determine whether survivor characteristics were associated with increased relative risk of death from other causes. METHODS: Using 3255 siblings as control subjects, the authors studied survival in a retrospective cohort study of 2319 adults who were at least 5-year survivors of cancer diagnosed before reaching 20 years of age and between 1945 and 1974 (the NCI Five Center Study). Follow-up occurred between 1980 and 1983 at a mean survivor age of 32 years (range, 21-55 years). RESULTS: Between cohort entry and follow-up, 292 (13%) survivors and 50 (2%) controls died. One-third of the deaths in survivors were from causes other than the primary malignancy. Compared with control subjects, between ages 21 and 40 years, survivors had a more than threefold risk of death from other causes. The relative risk (RR) for death from other causes was greatest for survivors treated with radiation and alkylating agents (RR = 6.1; 95% confidence interval [CI], 3.0-12.4) and for those treated with radiation alone (RR = 3.8; 95% CI, 2.3-6.2; Cox regression analysis containing terms for treatment and cancer diagnosis). CONCLUSIONS: Adult survivors of childhood and adolescent cancer had a higher death rate than their siblings, even after removing the effect of primary cancer as the direct cause. Moreover, death from other causes was most strongly associated with increasing intensity of therapy, and this excess risk did not diminish with increasing age and duration of cancer survival. Because contemporary anticancer therapy is, in general, even more intensive than that received by the survivors described in this study, medical surveillance of cancer survivors is increasingly important to diagnose and treat potentially life-threatening complications that may occur decades after therapy has ceased.

Adolescent↗
PubMed1992

Control sample size when cases are given in constant ratio stratum-matched case-control studies.

Strata-matched case-control studies based on a given number of cases and k times as many controls are common. We obtain a necessary and sufficient condition for there to exist a numerical solution for k with a desired level of a power. We derive the maximum power of the Cochran test, which may be less than one, when the number of cases is fixed. We provide an approximate formula for the minimum number of cases required for a specified power. There exists a numerical solution (that is, convergence of an iterative method) for k if the number of cases given is greater than this minimum number and no such a solution otherwise. We also show that the incremental gain in relative efficiency of the test with respect to k is diminished as k gets large.

Adult↗
PubMed1992

Optimum sample size determination in stratified case-control studies with cost considerations.

We investigate sample size determination for Cochran's test for stratified case-control studies when samples of cases and controls are allocated to maximize the asymptotic efficiency of Cochran's test subject to fixed total cost with cost per control varying by strata. We consider two situations typical of strata-matched case-control studies: when one samples both cases and controls and when cases are given and one samples controls. In each situation we develop and study an asymptotic method for finding the sample size required for a specific power under the optimum allocation proposed by Nam and Fears. Also, for the second situation, we investigate an asymptotic method for determining the common ratio, k, in one-to-k strata-matched case-control studies without cost consideration for a given power. When cases are given, neither the optimum nor the standard control sample sizes appear in a closed form; we present numerical methods for calculating these sample sizes and illustrate them with examples. We find the reduction in total cost obtained under the optimum allocation compared to standard allocation more pronounced as the differences in stratum-specific costs of sampling controls increase.

Adult↗
PubMed1992

Early menopause in long-term survivors of cancer during adolescence.

OBJECTIVE: We attempted to investigate the risk of early menopause after treatment for cancer during childhood or adolescence. STUDY DESIGN: We interviewed 1067 women in whom cancer was diagnosed before age 20, who were at least 5-year survivors, and who were still menstruating at age 21. Self-reported menopause status in survivors was compared with that in 1599 control women. RESULTS: Cancer survivors, with disease diagnosed between ages 13 and 19, had a risk of menopause four times greater than that of controls during the ages 21 to 25; the risk relative to controls declined thereafter. Significantly increased relative risks of menopause during the early 20s occurred after treatment with either radiotherapy alone (relative risk 3.7) or alkylating agents alone (relative risk 9.2). During ages 21 to 25 the risk of menopause increased 27-fold for women treated with both radiation below the diaphragm and alkylating agent chemotherapy. By age 31, 42% of these women had reached menopause compared with 5% for controls. CONCLUSION: Treatment for cancer during adolescence carries a substantial risk for early menopause among women still menstruating at age 21. Increasing use of radiation and chemotherapy, together with the continued trend toward delayed childbearing, suggests that these women should be made aware of their smaller window of fertility so that they can plan their families accordingly.

Adult↗
PubMed1991

Incidence of nonmelanoma skin cancer in New Hampshire and Vermont.

A survey of skin cancer occurrence between June 1979 and May 1980 among residents of New Hampshire and Vermont identified 277 cases of squamous cell carcinoma and 1761 cases of basal cell carcinoma. The age-adjusted incidence rates for squamous cell carcinoma (32 per 100,000 in men, 8 per 100,000 in women) and for basal cell carcinoma (159 per 100,000 in men, 87 per 100,000 in women) were similar to those reported in other populations in the northern United States. Skin cancer incidence was particularly high among men more than 70 years of age and a large proportion (greater than 30%) of patients 55 years or older had a history of at least one previous skin cancer.

Adolescent↗
PubMed1991

Growth of the great vessels in the normal human fetus and in the fetus with cardiac defects.

BACKGROUND: There is a paucity of quantitative anatomic data regarding human great vessel development that could be useful as a reference for fetal echocardiographers who must distinguish abnormal from normal cardiac development at early stages. METHODS AND RESULTS: To determine normal growth patterns, we plotted the diameters of the aortic and pulmonary valves, ductus arteriosus, aortic isthmus, and descending aorta in 274 autopsy specimens from nonselected spontaneous abortuses of normal karyotype. There was a linear increase in the diameters of these structures within the developmental period studied (10-26 weeks). A relative narrowing of the aorta at the isthmus compared with the aortic valve and descending aorta probably indicates that the majority of fetal left heart output goes to the developing heart and brain. In contrast to previous studies of late gestation and neonatal animals, however, we found that the diameter of the aortic isthmus was larger than that of the ductus arteriosus, suggesting substantial isthmic blood flow in these midtrimester fetuses. Among nineteen other hearts with diverse defects, both of two hearts with a narrow isthmus had an enlarged ductus arteriosus and one heart with pulmonary atresia/intact septum had a narrow ductus and increased aortic valve diameter. CONCLUSIONS: During midgestation, the normal heart may have substantial aortic isthmic blood flow that diminishes due to rerouting in late gestation when increased requirements of the fetal brain and other organs prevail. Although fetal shunts may explain some vessel abnormalities, the majority of cardiac defects in this study were not associated with abnormal growth of the great vessels within this developmental age range.

Aorta↗
PubMed1990

Smoking patterns by occupation and duration of employment.

Lifetime patterns of smoking and occupation based on personal interviews were examined among 3,627 white men and 1,200 white women who were randomly selected from ten areas in the United States during the period 1977-1978. These individuals participated in the control series of the National Bladder Cancer Study. We estimated, based on Axelson's method, the extent to which smoking habits for given occupational groups would confound the estimated relative risk for lung cancer for 62 occupations among men and 18 occupations among women. Among men, confounding by smoking resulted in a 30% or greater increased risk of lung cancer in only three occupational groups--namely, stationary engineers and power station operators (relative risk (RR) = 1.6), printers (RR = 1.3), and fishermen and sailors (RR = 1.3). A decrease in lung cancer risk of 0.8 or less due to smoking habits was observed among the clergy (RR = 0.5) and chemical workers (RR = 0.7). Among women, a 30% increase or greater in the risk of lung cancer based on smoking habits alone was found for food service workers (RR = 1.5), building managers and administrators (RR = 1.3), telephone and telegraph operators (RR = 1.3), and operatives (RR = 1.3). A risk ratio of 0.8 or less was observed for those women employed as farmers (RR = 0.5) and teachers (RR = 0.8). Smoking habits by duration of employment were also examined for 38 occupations among men. The largest increase in the risk of lung cancer based on the smoking habits among long-term workers was only 1.3 and was observed for those men employed 20 or more years as painters and as electricians. These findings suggest that the smoking patterns, in only a few occupational groups that we evaluated, confound estimates of the relative risk by more than 30%, and for most occupational groups under investigation in this study, confounding by smoking alone did not produce trends in relative risks by duration of employment.

Adult↗
PubMed1990

Optimum allocation of samples in strata-matching case-control studies when cost per sample differs from stratum to stratum.

We investigate the allocation of samples over strata in case-control studies with consideration of sampling costs. We consider two situations, typical of strata-matched case-control studies. Subject to a fixed total cost we derived optimum allocations that maximize the asymptotic efficiency of Cochran's test, that is, minimize the variance of the maximum likelihood estimator of the common odds ratio when the common odds ratio is one. Our results show that the standard design with equal numbers of cases and controls in each stratum is inefficient when costs per control differ greatly from stratum to stratum. We show that the optimum design suggested in this paper is robust for values of the odds ratio common in epidemiologic studies.

Case-Control Studies↗
PubMed1989

Marriage and divorce after childhood and adolescent cancer.

As part of a study of long-term survivors of childhood and adolescent cancer, we interviewed 2170 survivors and 3138 sibling control subjects about their marital histories. In a proportional hazards analysis, both male and female survivors were less likely to be ever married than control subjects (rate ratio [RR] for males, 0.87; 99% confidence interval, 0.76 to 0.99; RR for females, 0.86; 99% confidence interval, 0.76 to 0.97). Survivors of brain and central nervous system tumors accounted for most of the marriage deficit, which was greater in men than in women (RRs, 0.48 and 0.73, respectively). Survivors married at the same average age as control subjects, except for survivors of central nervous system tumors, who married slightly later. The average length of first marriages was shorter in survivors than in control subjects. Men who had survived central nervous system tumors diagnosed before 10 years of age and male survivors of retinoblastoma had higher divorce rates than male control subjects (RRs, 2.9 and 1.9, respectively). In this cohort (which received less intense therapy than given in current practice), altered marriage practices are substantial only among survivors of central nervous system tumors.

Adolescent↗
PubMed1989

The statistical analysis of a carcinogen mixture experiment. III. Carcinogens with different target systems, aflatoxin B1, N-butyl-N-(4-hydroxybutyl)nitrosamine, lead acetate, and thiouracil.

This paper describes factorial experiments designed to determine whether two carcinogens that lead to cancers in different organ systems act synergistically to produce cancers in Fischer 344 rats. Four carcinogens, aflatoxin B1 (AFLA), N-butyl-n-(4-hydroxybutyl)nitrosamine (NBBN), lead acetate (LA), and thiouracil (THIO) were studied in pairwise combinations. Each of the six possible pairs were studied by means of a 4 X 4 factorial experiment, each agent being fed at zero and at three non-zero doses. Methods of analysis designed explicitly for this study were derived to study interaction. These methods were supplemented by standard statistical methods appropriate for single agent studies. Neither synergism nor antagonism was demonstrated in these combined exposure studies. Findings for male and female animals were consistent.

Aflatoxin B1↗