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T Whelan

Publications and source records attributed to T Whelan.

29 records · Page 2Linked to original sources
PubMed1996

Randomized clinical trial of breast irradiation following lumpectomy and axillary dissection for node-negative breast cancer: an update. Ontario Clinical Oncology Group.

BACKGROUND: Breast-conservation surgery is now commonly used to treat breast cancer. Postoperative breast irradiation reduces cancer recurrence in the breast. There is still controversy concerning the necessity of irradiation of the breast in all patients. PURPOSE: We present an update of results from a randomized clinical trial designed to examine the efficacy of breast irradiation following conservation surgery in the treatment of women with axillary lymph node-negative breast cancer. The patients were enrolled from April 1984 through February 1989. Initial results were published in 1992 after a median follow-up time of 43 months. It was reported that recurrence of cancer in the breast occurred in 5.5% of the patients who received breast irradiation compared with 25.7% of those who did not. No difference in survival was detected between the two treatment groups. Now that the median patient follow-up has reached 7.6 years, the trial end points have been re-examined and an attempt has again been made to identify a group of patients at low risk for recurrence of cancer in the breast. METHODS: Eight hundred thirty-seven patients with node-negative breast cancer were randomly assigned to receive either radiation therapy (n = 416) or no radiation therapy (n = 421) following lumpectomy and axillary lymph node dissection. The cumulative local recurrence rate as a first event, distant recurrence (i.e., occurrence of metastasis) rate, and overall mortality rate for the treatment groups were described by the Kaplan-Meier method and compared with the use of the logrank test. The Cox proportional hazards model was used to adjust the observed treatment effect for the influence of various prognostic factors (patient age, tumor size, estrogen receptor level, and tumor histology) at study entry on the outcomes of local breast recurrence, distant recurrence, and overall mortality. All P values resulted from the use of two-tailed statistical tests. RESULTS: One hundred forty eight (35%) of the nonirradiated patients and 47 (11%) of the irradiated patients developed recurrent cancer in the breast (relative risk for patients in the former versus the latter group = 4.0; 95% confidence interval = 2.83-5.65; P < .0001). Ninety-nine (24%) of the patients in the former group have died compared with 87 (21%) in the latter group. Age (< 50 years), tumor size (> 2 cm), and tumor nuclear grade (poor) continued to be important predictors for local breast relapse. On the basis of these factors, we were unable to identify a subgroup of patients with a very low risk for local breast cancer recurrence. Tumor nuclear grade, as previously reported, and tumor size were important predictors for mortality. CONCLUSIONS: Breast irradiation was shown to reduce cancer recurrence in the breast, but there was no statistically significant reduction in mortality. A subgroup of patients with a very low risk for local breast recurrence who might not require radiation therapy was not identified.

Adult↗
PubMed1996

The role of palliative radiotherapy for brain metastases.

Brain metastases (BRM) are common complications of malignancy, frequently associated with disability and death. Clinical trials have addressed a few of the issues arising from treatment options for BRM. Phase III trials have shown superior survival for patients with solitary resectable BRM (SRBRM) when palliative radiation treatment (RT) to the brain is preceded by resection compared to brain RT alone, but no trial has explored resection plus brain RT compared to resection alone. One Phase III trial in patients with solitary unresected BRM comparing lower to higher doses of RT has shown a small survival advantage with higher-dose radiotherapy. All other trials, however, comparing different radiation doses and fractionation schedules have failed to indicate improved outcomes from treatment more intense than 2000 cGy in 5 fractions over 1 week (in any subset of patients with unresected BRM). A panel of radiation oncologists and medical oncologists discussed a literature review and results of Phase III trials of therapy for BRM. The panel was instructed to identify from these trials any evidence for the efficacy, indications, toxicity and fractionation of palliative RT for BRM. The panel concluded that unresected BRM is a possible indication for brain RT. The panel concluded that the benefits and toxicities of brain RT for unresected BRM are not characterized adequately to allow a stronger recommendation. The panel concluded that there is no evidence for superiority for any dose or schedule of brain RT for BRM more protracted or intense than 2000 cGy in 5 fractions over one week. The panel recommended further study in order to characterize the benefits and toxicities of brain RT for unresectable BRM. The panel considered the potential value of conducting a Phase III trial comparing palliative care and strategies that included brain RT to the same strategies excluding brain RT; the panel did not, however, reach consensus on the feasibility of such a trial.

Brain Neoplasms↗
PubMed1995

Primary carcinoid of the prostate in conjunction with multiple endocrine neoplasia IIb in a child.

Prostatic neoplasms are rare in childhood. We report a case of primary prostatic carcinoid in a 7-year-old boy who was subsequently diagnosed with multiple endocrine neoplasia IIb. To our knowledge this is the first report of either pediatric carcinoid of the prostate or of prostatic carcinoid in conjunction with neuronal intestinal dysplasia and medullary thyroid carcinoma suggestive of multiple endocrine neoplasia IIb. Management and histogenesis regarding this prostatic tumor are discussed as is a possible association with other neuroendocrine tumors.

Carcinoid Tumor↗
PubMed1994

Ipsilateral breast tumor recurrence postlumpectomy is predictive of subsequent mortality: results from a randomized trial. Investigators of the Ontario Clinical Oncology Group.

PURPOSE: To determine whether ipsilateral breast tumor recurrence (IBTR) postlumpectomy was independently predictive of distant relapse and mortality in women with node negative breast cancer. METHODS AND MATERIALS: A randomized trial was conducted in Ontario between 1984 and 1989, in which 837 women with node negative disease who had undergone lumpectomy and axillary dissection were randomized to either postoperative radiation (40 Gy in 16 fractions to the whole breast, followed by a boost of 12.5 Gy in five fractions to the primary site), or no further treatment. A Cox proportional hazards regression analysis was performed for the endpoints mortality and distant relapse using the fixed covariates, treatment, age, tumor size, estrogen receptor status, progesterone receptor status, and nuclear grade; and the time dependent variable IBTR. RESULTS: The analysis was based on 799 patients for which all fixed covariate data was available. Median follow-up was 66 months. The cumulative rate of IBTR at 5 years was significantly greater for the no treatment group compared to the radiation group; 30% vs. 8% respectively (p < 0.0001). No difference was detected in overall survival between the treatment groups (p = 0.45). Significant independent predictors for mortality were nuclear grade, high vs. medium or low (relative risk (RR) = 2.28, p = 0.0001); and tumor size > or = 2 cm. vs. < 2 cm. (RR = 1.64, p = 0.01). In addition, IBTR predicted increased mortality (RR = 2.18, p < 0.0006). Similar results were observed for distant relapse. An IBTR within 1 year of surgery was associated with a higher risk of distant relapse and mortality. CONCLUSION: Local breast recurrence following lumpectomy is associated with an increased risk of distant relapse and death.

Breast Neoplasms↗
PubMed1994

Patient preference for high or low dose rate brachytherapy in carcinoma of the cervix.

High and low dose rate are two competing methods of brachytherapy. Existing data do not support choosing one method over the other for treating carcinoma of the uterine cervix. Arguments include clinical efficacy, monetary cost, radiation safety, and patient preference. There are no published data on patient preference. We developed a questionnaire to elicit patient preference and to measure its strength. Subjects received descriptions of both treatment options and their probable outcomes. We elicited preference for one low or three high dose rate fractions, and for two low or five high dose rate fractions, assuming both methods to be isoeffective. Strength of initial preference was measured by asking subjects how much of a change, in either the changes for cure or the chances for toxicity, would make them change preference. The questionnaire was completed by female staff at our centre (n = 90), by a group of previously treated patients (n = 18), and by a group of newly diagnosed patients (n = 20). When both methods were assumed to be isoeffective, only 34% of the 38 patients preferred three fractions of high dose rate to one fraction of low dose rate. However, when high dose rate was assumed to be 2% more curative, or 6% less toxic, a simple majority of 50% then said they would prefer high dose rate. Both preference and strength of preference for low dose rate were significantly associated with a greater travelling distance for treatments. Age, marital status, family structure, education, employment, and family income were not associated. In summary, a majority of our patients preferred low dose rate brachytherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Adjuvant radiotherapy for early breast cancer: patterns of practice in Ontario.

OBJECTIVE: To determine the number of different radiation schedules used in Ontario to treat women with node-negative breast cancer after lumpectomy and axillary dissection. DESIGN: Retrospective survey. SETTING: Princess Margaret Hospital, Toronto, and regional centres of the Ontario Cancer Treatment and Research Foundation (in Hamilton, London, Ottawa, Windsor and Thunder Bay). PATIENTS: A total of 551 of 1624 consecutive patients with node-negative breast cancer having undergone lumpectomy and axillary dissection who were eligible but did not participate in the Ontario Clinical Oncology Group randomized clinical trial and who received adjuvant breast irradiation between April 1984 and February 1989. OUTCOME MEASURES: Schedules of radiotherapy received. RESULTS: Forty-eight different radiotherapy schedules were identified. Total doses ranged from 4000 to 6600 cGy and the number of fractions from 15 to 30. Several different schedules were preferred: 322 patients (58.5%) received 4000 cGy in 15 or 16 fractions to the whole breast over 3 weeks plus a local boost of 1250 cGy to the primary site in 5 fractions over 1 week; 66 patients (12.0%) received 4000 cGy in 15 or 16 fractions over 3 weeks to the whole breast plus a local boost of 1000 cGy to the primary site in 4 or 5 fractions over 1 week; and 63 patients (11.5%) received 5000 cGy in 25 fractions to the whole breast in 5 weeks, without a boost. CONCLUSIONS: The practice of adjuvant radiotherapy for early breast cancer in Ontario varies. The optimal radiation regimen for patients after lumpectomy should be determined through randomized clinical trials.

Breast Neoplasms↗
PubMed1975

Microbial indicators of oil-rich salt marsh sediments.

Selected microbial parameters were monitored in sediments from a pristine and an oil-field salt marsh. Although numbers of hydrocarbonoclastic bacteria and fungi were significantly greater in the oil field, the values did not show a strong correlation with levels of hydrocarbons (r = 0.43 and r = 0.49, respectively). However, a high correlation was noted between ratios of hydrocarbonoclastic and total aerobic heterotrophic bacteria and levels of hydrocarbons as well as the relative concentration of hydrocarbons (ratio of hydrocarbons to chloroform extractables) (r = 0.87 and r = 0.77, respectively). Data suggest that this first ratio is a more valid microbial indicator of hydrocarbon abundance than other factors examined. Significant differences in the ratio of pigmented to total colony-forming units, the ratio of different to total colony-forming units, and the diversity index were noted between the natural and oil-field marsh. It is suggested that the presence of hydrocarbons alters the relative abundance of the most predominant aerobic heterotrophic bacteria.

Journal Article↗
PubMed1973

Enzymatic fractionation of carbon isotopes by phosphoenolpyruvate carboxylase from c(4) plants.

The carbon atoms of glucose and malate in C(4) plants are 2 to 3 per thousand enriched in (12)C with respect to atmospheric CO(2); whereas these intermediates in C(3) plants are 15 to 18 per thousand enriched with (12)C with respect to atmospheric CO(2). The enzymatic synthesis of malate from phosphoenolpyruvate and bicarbonate in preparations of leaves of Sorghum bicolor, Haygrazer result in a carbon isotope fractionation of about 3 per thousand. The enzymatic synthesis of phosphoglyceric acid from ribulose 1,5-diP and CO(2) in these preparations (contaminated with carbonic anhydrase) at 24 C and 37 C result in a carbon isotope fractionation of 33.7 per thousand and 18.3 per thousand, respectively. These data are consistent with the conclusion that the small enrichment of (12)C in the carbon atoms of malate and glucose (with respect to atmospheric CO(2)) in leaves of Sorghum bicolor, Haygrazer occurs at the phosphoenolpyruvate carboxylase step.

Journal Article↗