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Biomedical subjects

C B Begg

Publications and source records attributed to C B Begg.

At least 19 recordsLinked to original sources
PubMed2004

Estimating the relative risk of developing melanoma in INK4A carriers.

Estimation of the relative risk of cancer due to rare germline mutations using population-based epidemiological techniques is challenging, since studies with very large numbers of subjects are required. In this pilot study using a novel study design, we evaluated the role of INK4A mutations in melanoma by comparing patients with multiple primary melanomas to those with single primaries. Patients were ascertained from the Surgery and Dermatology Clinics at Memorial Sloan-Kettering Cancer Center and at the Yale University Pigmented Lesion Clinic. Subjects completed a questionnaire covering risk factors for melanoma and were tested for INK4A mutations. Five (8%) of 65 patients with multiple primaries had a mutation, compared with none of 88 patients with single primaries (P=0.03). Examination of other factors, such as number of nevi on the arms of the patients, fair skin, hair and eye colour, and other phenotypic characteristics associated with the risk of melanoma, demonstrates that these factors exhibit higher prevalence in the multiple primary cases than in the single primaries. These results provide evidence of the utility of the new study design in evaluating the impact of rare but highly penetrant cancer risk factors.

Adolescent↗
PubMed2001

Who gets adjuvant treatment for stage II and III rectal cancer? Insight from surveillance, epidemiology, and end results--Medicare.

PURPOSE: To examine the relationship between patient characteristics and the use of adjuvant pelvic radiation with and without chemotherapy among patients aged 65 years and older with stage II and III rectal cancer. PATIENTS AND METHODS: A retrospective cohort study using the Surveillance, Epidemiology, and End Results-Medicare linked database identified 1,411 patients aged 65 and older with resected stage II and III rectal cancers diagnosed between 1992 and 1996. From claims submitted to Medicare, we measured the use of pelvic radiation therapy with or without chemotherapy and pre- or postoperatively. RESULTS: Fifty-seven percent of patients received radiation, 42% received chemotherapy and radiation, and 7% had treatment delivered preoperatively. Age was the strongest determinant of treatment: 73% of patients aged 65 to 69, 66% aged 70 to 75, 52% aged 75 to 79, 39% aged 80 to 84, and 21% aged 85 to 89 received radiation. The age trend remained strong after adjusting for other factors that predict receipt of treatment and after exclusion of patients with any evident comorbidity (P <.001). Patients were more likely to receive radiation treatment if they had an abdominal perineal resection, stage III disease, or a T4 tumor. CONCLUSION: Because pelvic recurrences are a substantial cause of morbidity, further efforts are needed to ensure that elderly patients have the opportunity to make informed decisions regarding adjuvant treatment.

Age Factors↗
PubMed2001

The influence of hospital volume on survival after resection for lung cancer.

BACKGROUND: Among patients who have undergone high-risk operations for cancer, postoperative mortality rates are often lower at hospitals where more of these procedures are performed. We undertook a population-based study to estimate the extent to which the number of procedures performed at a hospital (hospital volume) is associated with survival after resection for lung cancer. METHODS: We studied patients 65 years old or older who received a diagnosis of stage I, II, or IIIA non-small-cell lung cancer between 1985 and 1996, resided in 1 of the 10 study areas covered by the Surveillance, Epidemiology, and End Results Program, and underwent surgery at a hospital that participates in the Nationwide Inpatient Sample (2118 patients and 76 hospitals). RESULTS: The volume of procedures at the hospital was positively associated with the survival of patients (P<0.001). Five years after surgery, 44 percent of patients who underwent operations at the hospitals with the highest volume were alive, as compared with 33 percent of those who underwent operations at the hospitals with the lowest volume. Patients at the highest-volume hospitals also had lower rates of postoperative complications (20 percent vs. 44 percent) and lower 30-day mortality (3 percent vs. 6 percent) than those at the lowest-volume hospitals. CONCLUSIONS: Patients who undergo resection for lung cancer at hospitals that perform large numbers of such procedures are likely to survive longer than patients who have such surgery at hospitals with a low volume of lung-resection procedures.

Aged↗
PubMed2001

Age and adjuvant chemotherapy use after surgery for stage III colon cancer.

BACKGROUND: Randomized trials have established that 5-fluorouracil-based adjuvant chemotherapy following resection of stage III colon cancer reduces subsequent mortality by as much as 30%. However, the extent to which adjuvant therapy is used outside the clinical trial setting, particularly among the elderly, is unknown. METHODS: A retrospective cohort study utilizing the Surveillance, Epidemiology, and End Results/Medicare-linked database identified 6262 patients aged 65 years and older with resected stage III colon cancer. The primary outcome was chemotherapy use within 3 months of surgery, as ascertained from Medicare claims. We examined the extent to which age at diagnosis was associated with adjuvant chemotherapy usage, and we adjusted for potential confounding based on differences in other patient characteristics with the use of multiple logistic regression. All P values were two-sided. RESULTS: Age at diagnosis was the strongest determinant of chemotherapy: 78% of patients aged 65-69 years, 74% of those aged 70-74 years, 58% of those aged 75-79 years, 34% of those aged 80-84 years, and 11% of those aged 85-89 years received postoperative chemotherapy. The age trend remained pronounced after adjustment for potential confounding based on variation in patients' demographic and clinical characteristics and after exclusion of patients with any evident comorbidity (all P values <.001). CONCLUSIONS: Adjuvant chemotherapy for stage III colon cancer is used extensively, especially for patients under the age of 75 years. However, treatment rates decline dramatically with chronologic age. Because patients in their 70s and even 80s have a reasonable life expectancy, further efforts are needed to ensure that elderly patients have the opportunity to make informed decisions regarding this potentially curative treatment.

Age Distribution↗
PubMed2001

The search for cancer risk factors: when can we stop looking?

In recent decades, countless cohort, case-control, and ecologic studies have been conducted in the search for cancer risk factors. On the basis of knowledge gained from these studies, various influential commentaries have endeavored to classify the extent to which the total cancer burden is attributable to general categories of risk, such as diet, tobacco, sun exposure, and others. These commentaries have led to the conventional wisdom that most of the cancer burden is caused by environmental factors and relatively little is directly attributable to genetic susceptibility. In the face of the apparent knowledge that the cancer burden is essentially fully "explainable" on the basis of known environmental risks, this article addresses the conceptual and empirical basis of the continued search for new risk factors. It proposes that the extent of the aggregation of cancer within individuals in the population--that is, the occurrence of second primary cancers--is a crucial statistic in this context. A study of the incidence of second primary melanoma suggests that the bulk of the risk variation in this disease cannot be explained by known risk factors. The implications of these ideas for research strategy and for public health policy are discussed.

Adult↗
PubMed2001

The lifetime risks of breast cancer in Ashkenazi Jewish carriers of BRCA1 and BRCA2 mutations.

Several studies using families with multiple occurrences of breast cancer have provided evidence for a very high lifetime penetrance in carriers of BRCA1 or BRCA2 mutations. However, there are reasons to suspect that the estimates of penetrance from studies of cancer families may be inflated. Access to the genotypes of incident cases of breast cancer in three hospitals and from a large series of unaffected survey participants provided the basis for direct estimation of the age-specific relative risks attributable to these mutations, and the resulting lifetime penetrance, without any reference to familial aggregation of cancer. Cases were identified from incident series of Jewish patients treated for primary breast cancer at the three hospitals. Control data were obtained from the large series of Jewish women recruited in the Washington, D.C., area by investigators at the National Cancer Institute and limited to 3434 women with no previous history of breast or ovarian cancer. All subjects were genotyped for the three mutations that are relatively common in Ashkenazi Jews, namely 185delAG and 5382 insC in BRCA1 and 6174delT in BRCA2. For BRCA1, the relative risks of breast cancer were estimated to be 21.6 in women under 40 years of age, 9.6 in women 40-49 years of age, and 7.6 in women > or = 50 years of age. On the basis of these estimates, the penetrance of breast cancer at age 70 among BRCA1 mutation carriers is estimated to be 46% (95% confidence, 31%-80%) rising to 59% (95% confidence, 40%-93%) at age 80. For BRCA2, the relative risks in the same three age categories were estimated to be 3.3, 3.3, and 4.6, respectively, resulting in a penetrance at age 70 of 26% (95% confidence, 14%-50%) rising to 38% (95% confidence, 20%-68%) at age 80. The lifetime risk of breast cancer in Jewish women who are mutation carriers estimated via this approach is substantially lower than the reported lifetime risks estimated using multiple-case families. The risks appear to be different for carriers of BRCA1 and BRCA2 mutations.

Adult↗
PubMed2000

Influence of hospital procedure volume on outcomes following surgery for colon cancer.

CONTEXT: Survival following high-risk cancer surgery, such as pancreatectomy and esophagectomy, is superior at hospitals where high volumes of these procedures are performed. Conflicting evidence exists as to whether the association between hospital experience and favorable health outcomes also applies to more frequently performed operations, such as those for colon cancer. OBJECTIVE: To determine whether hospital procedure volume predicts survival following colon cancer surgery. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cohort study of data from the Surveillance, Epidemiology and End Results-Medicare linked database on 27 986 colon cancer patients aged 65 years and older who had surgical resection for primary adenocarcinoma diagnosed between 1991 and 1996. MAIN OUTCOME MEASURES: Thirty-day postoperative mortality and overall and cancer-specific long-term survival, by hospital procedure volume. RESULTS: We found small differences in 30-day postoperative mortality for patients treated at low- vs high-volume hospitals (3. 5% at hospitals in the top-volume quartile vs 5.5% at hospitals in the bottom-volume quartile). However, the correlation was statistically significant and persisted after adjusting for age at diagnosis, sex, race, cancer stage, comorbid illness, socioeconomic status, and acuity of hospitalization (P<.001). The association was evident for subgroups with stage I, II, and III disease. Hospital volume directly correlated with survival beyond 30 days and also was not attributable to differences in case mix (P<.001). The association between hospital volume and long-term survival was concentrated among patients with stage II and III disease (P<.001 for both). Among stage III patients, variation in use of adjuvant chemotherapy did not explain this finding. CONCLUSION: Our data suggest that hospital procedure volume predicts clinical outcomes following surgery for colon cancer, although the absolute magnitudes of these differences are modest in comparison with the variation observed for higher-risk cancer surgeries.

Adenocarcinoma↗
PubMed2000

Comparing tumour staging and grading systems: a case study and a review of the issues, using thymoma as a model.

We consider the problem of comparing alternative cancer staging and grading systems. Statistical comparisons are on the basis of the ability to predict survival, but more qualitative criteria, such as parsimony, and distinctive prognostic separability of the categories are relevant also. Furthermore, some staging systems are clearly ordinal, while others are not. Three candidate statistical measures are studied and compared: explained variation; area under the ROC curve; and the probability of concordance of stage and survival. Each of these has individual strengths and weaknesses. A data set involving the staging of thymoma is analysed in detail to motivate the problem and illustrate the results.

Classification↗
PubMed1999

Racial differences in the treatment of early-stage lung cancer.

BACKGROUND: If discovered at an early stage, non-small-cell lung cancer is potentially curable by surgical resection. However, two disparities have been noted between black patients and white patients with this disease. Blacks are less likely to receive surgical treatment than whites, and they are likely to die sooner than whites. We undertook a population-based study to estimate the disparity in the rates of surgical treatment and to evaluate the extent to which this disparity is associated with differences in overall survival. METHODS: We studied all black patients and white patients 65 years of age or older who were given a diagnosis of resectable non-small-cell lung cancer (stage I or II) between 1985 and 1993 and who resided in 1 of the 10 study areas of the Surveillance, Epidemiology, and End Results (SEER) program (10,984 patients). Data on the diagnosis, stage of disease, treatment, and demographic characteristics of the patients were obtained from the SEER data base. Information on coexisting illnesses, type of Medicare coverage, and survival was obtained from linked Medicare inpatient-discharge records. RESULTS: The rate of surgery was 12.7 percentage points lower for black patients than for white patients (64.0 percent vs. 76.7 percent, P<0.001), and the five-year survival rate was also lower for blacks (26.4 percent vs. 34.1 percent, P<0.001). However, among the patients undergoing surgery, survival was similar for the two racial groups, as it was among those who did not undergo surgery. Furthermore, analyses in which adjustments were made for factors that are predictive of either candidacy for surgery or survival did not alter the influence of race on these outcomes. CONCLUSIONS: Our analyses suggest that the lower survival rate among black patients with early-stage, non-small-cell lung cancer, as compared with white patients, is largely explained by the lower rate of surgical treatment among blacks. Efforts to increase the rate of surgical treatment for black patients appear to be a promising way of improving survival in this group.

Aged↗
PubMed1999

Properties of a nonparametric test for early comparison of treatments in clinical trials in the presence of surrogate endpoints.

A nonparametric test is derived for comparing treatments with respect to the final endpoint in clinical trials in which the final endpoint has been observed for a random subset of patients, but results are available for a surrogate endpoint for a larger sample of patients. The test is an adaptation of the Wilcoxon-Mann-Whitney two-sample test, with an adjustment that involves a comparison of the ranks of the surrogate endpoints between patients with and without final endpoints. The validity of the test depends on the assumption that the patients with final endpoints represent a random sample of the patients registered in the study. This assumption is viable in trials in which the final endpoint is evaluated at a "landmark" timepoint in the patients' natural history. A small sample simulation study demonstrates that the test has a size that is close to the nominal value for all configurations evaluated. When compared with the conventional test based only on the final endpoints, the new test delivers substantial increases in power only when the surrogate endpoint is highly correlated with the true endpoint. Our research indicates that, in the absence of modeling assumptions, auxiliary information derived from surrogate endpoints can provide significant additional information only under special circumstances.

Biometry↗
PubMed1999

Phase III multicenter randomized trial of the Dartmouth regimen versus dacarbazine in patients with metastatic melanoma.

PURPOSE: Several single-institution phase II trials have reported that the Dartmouth regimen (dacarbazine, cisplatin, carmustine, and tamoxifen) can induce major tumor responses in 40% to 50% of stage IV melanoma patients. This study was designed to compare the overall survival time, rate of objective tumor response, and toxicity of the Dartmouth regimen with standard dacarbazine treatment in stage IV melanoma patients. PATIENTS AND METHODS: In this multicenter phase III trial, 240 patients with measurable stage IV melanoma were randomized to receive the Dartmouth regimen (dacarbazine 220 mg/m(2) and cisplatin 25 mg/m(2) days 1 to 3, carmustine 150 mg/m(2) day 1 every other cycle, and tamoxifen 10 mg orally bid) or dacarbazine 1, 000 mg/m(2). Treatment was repeated every 3 weeks. Patients were observed for tumor response, survival time, and toxicity. RESULTS: Median survival time from randomization was 7 months; 25% of the patients survived > or = 1 year. There was no difference in survival time between the two treatment arms when analyzed on an intent-to-treat basis or when only the 231 patients who were both eligible and had received treatment were considered. Tumor response was assessable in 226 patients. The response rate to dacarbazine was 10.2% compared with 18.5% for the Dartmouth regimen (P =.09). Bone marrow suppression, nausea/vomiting, and fatigue were significantly more common in the Dartmouth arm. CONCLUSION: There was no difference in survival time and only a small, statistically nonsignificant increase in tumor response for stage IV melanoma patients treated with the Dartmouth regimen compared with dacarbazine. Dacarbazine remains the reference standard treatment for stage IV melanoma.

Adult↗
PubMed1999

Staging of malignant pleural mesothelioma: comparison of CT and MR imaging.

OBJECTIVE: This article compares the accuracy of CT with that of MR imaging in staging of malignant pleural mesothelioma. SUBJECTS AND METHODS: Ninety-five patients were enrolled in a prospective staging protocol based on the International Mesothelioma Interest Group staging system. Sixty-five patients underwent CT and MR imaging and a surgical procedure (excluding percutaneous needle biopsy) to stage and resect the tumor. Receiver operating characteristic analyses were performed. CT and MR scans were interpreted independently by observers who were unaware of the results of the other imaging study; these imaging findings were compared with the results of surgery and pathologic examination. RESULTS: The areas under the receiver operating characteristic curves for eight of 10 features revealed by imaging showed no statistically significant differences between CT and MR imaging. However, MR imaging was superior to CT in revealing invasion of the diaphragm (A(z) = .55 for CT versus .82 for MR imaging) and in revealing invasion of endothoracic fascia or solitary resectable foci of chest wall invasion (A(z) = .46 for CT; A(z) = .69 for MR imaging). Several anatomic regions could not be evaluated because positive findings at surgery were rare. CONCLUSION: CT and MR imaging are of nearly equivalent diagnostic accuracy in staging malignant pleural mesothelioma. MR imaging is superior to CT in revealing solitary foci of chest wall invasion and endothoracic fascia involvement and in showing diaphragmatic muscle invasion; however, this advantage does not affect surgical treatment. For cost reasons, CT should be considered the standard diagnostic study before therapy.

Adult↗
PubMed1998

Impact of hospital volume on operative mortality for major cancer surgery.

CONTEXT: Hospitals that treat a relatively high volume of patients for selected surgical oncology procedures report lower surgical in-hospital mortality rates than hospitals with a low volume of the procedures, but the reports do not take into account length of stay or adjust for case mix. OBJECTIVE: To determine whether hospital volume was inversely associated with 30-day operative mortality, after adjusting for case mix. DESIGN AND SETTING: Retrospective cohort study using the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database in which the hypothesis was prospectively specified. Surgeons determined in advance the surgical oncology procedures for which the experience of treating a larger volume of patients was most likely to lead to the knowledge or technical expertise that might offset surgical fatalities. PATIENTS: All 5013 patients in the SEER registry aged 65 years or older at cancer diagnosis who underwent pancreatectomy, esophagectomy, pneumonectomy, liver resection, or pelvic exenteration, using incident cancers of the pancreas, esophagus, lung, colon, and rectum, and various genitourinary cancers diagnosed between 1984 and 1993. MAIN OUTCOME MEASURE: Thirty-day mortality in relation to procedure volume, adjusted for comorbidity, patient age, and cancer stage. RESULTS: Higher volume was linked with lower mortality for pancreatectomy (P=.004), esophagectomy (P<.001), liver resection (P=.04), and pelvic exenteration (P=.04), but not for pneumonectomy (P=.32). The most striking results were for esophagectomy, for which the operative mortality rose to 17.3% in low-volume hospitals, compared with 3.4% in high-volume hospitals, and for pancreatectomy, for which the corresponding rates were 12.9% vs 5.8%. Adjustments for case mix and other patient factors did not change the finding that low volume was strongly associated with excess mortality. CONCLUSIONS: These data support the hypothesis that when complex surgical oncologic procedures are provided by surgical teams in hospitals with specialty expertise, mortality rates are lower.

Aged↗
PubMed1997

Planning controlled clinical trials. Prostatic cancer.

OBJECTIVE: To address principles in the design and conduct of clinical trials on prostate cancer (PC) with special reference to localized disease. METHODS: In advance of and during the World Health Organization (WHO) conference on Prostate Cancer in Stockholm in September 1996, 6 members of a working group evaluated and reached consensus on key points for the planning and conduction of controlled clinical trials in PC. The key points discussed were 1) hypothesis formulation, 2) general methodological principles, 3) special problems of PC trials, 4) alternatives to randomization, and 5) trial organization. RESULTS: The hypothesis must be clearly formulated and also clinically relevant enough to justify the expenses (in a broad sense) of a randomized clinical trial. Patient selection, definition of endpoints, and sample size calculations must be carefully considered and correspond to the aims of the study. Stratification on important prognostic factors should be contemplated. Maintaining the accrual rate and ensuring compliance are critical for a quality study. Survival is the main endpoint and intention to treat analysis is the standard methodology. Secondary endpoints (eg, quality of life and costs) are important for the evaluation of many treatment modalities. The use of surrogate endpoints for survival, such as prostate-specific antigen (PSA) elevation, may be misleading. Surrogate endpoints require further validation. Special features, such as long natural history in localized disease and difficulties in assessing objective responses in advanced disease, need consideration in PC trials. The controlled randomized trial is the gold standard methodology. Nonrandomized trials are often hampered by severe methodological problems, such as selection bias and biased ascertainment of endpoints due to the doctor's or patient's preferences. For the organization of a successful trial, a well-constructed study protocol is essential. Good clinical practice as defined within the European Community helps define and solve practical problems. CONCLUSIONS: The past 30 years of poorly designed clinical research on PC has left us without reliable answers in key clinical issues regarding, for example, the efficacy of primary treatment of localized PC. It is a stimulating and important challenge to the urological scientific community to conduct well-organized controlled clinical trials.

Controlled Clinical Trials as Topic↗
PubMed1997

The indications, rationale, and results of neoadjuvant androgen deprivation in the treatment of prostatic cancer: Memorial Sloan-Kettering Cancer Center results.

OBJECTIVES: The use of neoadjuvant chemotherapy prior to definitive surgery has been firmly established in other areas of oncology, most notably in the treatment to testis and Wilm's tumors. The use of neoadjuvant androgen deprivation therapy (ADT) in conjunction with radical prostatectomy remains a source of controversy. We have conducted phase II and phase III studies to assess the effects of 3 months of preoperative ADT (goserelin and flutamide) on the pathologic staging and postsurgery prostate-specific antigen (PSA) relapse rate. We also reviewed the data confirming the understaging of clinically localized prostatic cancer and the experimental data providing the conceptual support for ADT. METHODS: We report the results of 141 patients, Stage T0-T0, in a Phase II study with concurrent, nonrandomized controls (N = 72) versus a treatment arm (N = 69) of men receiving 3 months of ADT with 3.6 mg goserelin for 28 days and 750 mg flutamide daily. We also report the interim results in 114 men participating in a prospective, randomized study of ADT versus surgery alone. RESULTS: The 69 patients who received 3 months of goserelin and flutamide followed by radical prostatectomy had a pathologic organ-confined cancer rate of 74%, versus 48% in the control group who received no ADT prior to surgery. The margin-positive rate was 10% in the ADT group versus 33% in the control group. In an interim analysis of 114 patients (59 ADT, 55 control), the organ-confined and margin-positive rates were 73% and 17% in the ADT group versus 56% and 36% in the control arm, respectively. The PSA disease-free rate at a mean follow-up of 28.6 months (range 6.2 to 49.5 months) was 89% in the ADT-treated patients (N = 98) and 84% in the control patients (N = 96). There was no statistical difference demonstrated between the arms with respect to biochemical failure. CONCLUSIONS: While the pathologic staging of tumors following ADT treatment was improved compared with surgical controls, to date the PSA disease-free survival rates are similar. Patients with residual extracapsular (P3) disease after ADT manifest an increased PSA failure rate compared with those with P3 tumors treated by surgery alone. This suggests that ADT may identify a subset of patients with aggressive tumors that may be candidates for additional therapeutic interventions even before PSA failure occurs.

Aged↗
PubMed1997

Pathological staging and biochemical recurrence after neoadjuvant androgen deprivation therapy in combination with radical prostatectomy in clinically localized prostate cancer: results of a phase II study.

OBJECTIVES: To assess the pathological staging and biochemical progression-free survival (assessed using serum prostate-specific antigen level) of patients with clinically localized prostate cancer using neoadjuvant androgen deprivation therapy (ADT) in combination with radical retropubic prostatectomy (RRP). PATIENTS AND METHODS: A prospective study was carried out on 69 patients with localized prostate cancer who were enrolled in a trial of 3 months of ADT followed by RRP (group 1). These patients were compared with 72 patients matched for age and clinical stage who declined ADT therapy and had RRP concurrently (group 2). Assignment to the individual treatment groups was thus determined by the patient's preference and not the physician's selection. Pathological staging and biochemical progression-free recurrence were compared between the groups. RESULTS: The rate of organ-confined (pT2) tumours was 74% in group 1 and 49% in group 2 (P < 0.01), and the rate of margin-negative tumours was 87% in group 1 and 64% in group 2 (P < 0.01). Within a median follow-up of 35 months, there was no significant difference in biochemical failure between the groups (P = 0.37). Patients with pT2 disease, regardless of treatment, had similar biochemical failure rates. In the patients with margin-positive disease, there was a significantly higher biochemical failure rate in group 1 (P = 0.02). CONCLUSIONS: The rates of organ- and specimen-confined disease were higher among the patients treated with ADT. The preliminary follow-up suggested that patients with pT2 disease after ADT have a biochemical progression-free recurrence rate similar to pT2 patients treated with RRP alone. Additionally, high biochemical failure rates in patients with margin-positive disease after ADT may identify a subset of more biologically aggressive tumours in need of early adjuvant treatment.

Aged↗