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Biomedical subjects

B Vikram

Publications and source records attributed to B Vikram.

At least 37 records · Page 2Linked to original sources
PubMed1999

Brachytherapy in cancer of the head and neck.

This article provides a review of the general principles of brachytherapy for tumors in the head and neck. The different radionuclides used for this technique are discussed, as are the different capacities in which brachytherapy can be used, such as intraoperatively, as an adjuvant to surgery, to control nasopharyngeal carcinoma, following chemoradiotherapy, and for management of recurrent cancers.

Brachytherapy↗
PubMed1999

Experience-based demand scheduling: a more efficient model for radiation oncology.

The supply of radiation therapists has increased, whereas reimbursements have decreased. One hypothesis is that if we choose to employ as permanent staff sufficient therapists to handle the low-volume periods and scheduled temporary staff as the demand for radiation therapy services warrants, we would increase efficiency. Using current economic assumptions and the treatments delivered during the past 12 months, we analyzed the labor expense and revenue consequences of both full staffing and a lower level of staffing with per diem supplementation based on the scheduled patient load. We then correlated the scheduled treatments with the actual treatments delivered and finally, reexamined both the full-staffing model and the per diem supplementation model based on the predictions of our scheduling model. The reduction in full-time therapists and per diem supplementation did not produce substantial incremental revenue. However, examining the relationship between patients scheduled for treatment on the next day and patients actually treated, revealed an 11% "no show" rate with a 95% confidence interval of 1%. Our new, experienced-based model demonstrated considerable revenues to be realized by using the no-show factor to better use therapists by more aggressive scheduling of outpatients, therapists, and more flexible transportation of inpatients. We conclude that the experience-based model predicts the marginal revenue, but is silent on the quality of the medical care provided.

Appointments and Schedules↗
PubMed1999

Breast cancer screening in underserved women in the Bronx.

This article reports the results of mammography screening among socioeconomically disadvantaged women in Bronx, NY using a federally funded low-cost or no-cost cancer screening service. The New York State Department of Health provided funds for the uninsured through the Bronx Breast Health Partnership. All women < or = 40 years underwent screening mammography using both a mobile van unit and hospital-based mammographic x-ray unit, both American College of Radiology (ACR) accredited. Return visits were coordinated by a follow-up clinic at Montefiore Medical Center using a patient navigator who acted as an advocate for patients with abnormal screening findings. The overall detection rate of 12.9 per 1000 women screened was significantly higher than the New York State detection rate of 6 per 1000 and 5.1 per 1000 nationally. Availability of a patient navigator was an essential factor in the effectiveness of the work-up of problem cases. Low-cost or no-cost breast cancer screening programs can improve the availability, accessibility, acceptability, and utilization of mammography among underserved and uninsured women who are least likely to be screened otherwise.

Adult↗
PubMed1998

Anemia is associated with decreased survival and increased locoregional failure in patients with locally advanced head and neck carcinoma: a secondary analysis of RTOG 85-27.

PURPOSE: The purpose of the present study is to investigate the strength of association between anemia and overall survival, locoregional failure, and late radiation therapy (RT) complications in a large prospective study of patients with advanced head and neck cancer treated with conventional radiotherapy with or without a hypoxic cell sensitizer. METHODS AND MATERIALS: Between March 1988 and September 1991, 521 patients with Stage III or IV squamous cell carcinoma of the head and neck were entered into a randomized trial examining the addition of etanidazole (SR 2508) to conventional radiation therapy (RT) (66-74 Gy in 33-37 fractions, 5 days a week). Patients with hemoglobin (Hgb) levels measured and recorded prior to the second week of RT were included in this secondary analysis. Hemoglobin levels were stratified as normal (> or = 14.5 gm% for men, > or = 13 gm% for women) or anemic (< 14.5 gm% for men, < 13 gm% for women). Locoregional failure rates were calculated using the cumulative incidence approach. Overall survival was estimated according to the Kaplan-Meier method. Late RT toxicity was scored according to the RTOG morbidity scale. Differences in rates of overall survival, locoregional failure, and late complications were tested by the Cox proportional hazard model. RESULTS: Of 504 eligible patients, 451 had a Hgb level measured and recorded prior to the second week of RT. One hundred sixty-two patients (35.9%) were considered to have a normal Hgb level and 289 patients (64.1%) were considered to be anemic. The estimated survival rate is 35.7% at 5 years in patients with a normal Hgb, versus 21.7% in anemic patients (p = 0.0016). The estimated locoregional failure rate is 51.6% at 5 years in patients with a normal Hgb, versus 67.8% in anemic patients (p = 0.00028). The estimated rate of grade 3 or greater toxicity is 19.8% at 5 years in patients with a normal Hgb, versus 12.7% in anemic patients (p = 0.063). On multivariate analysis, several variables were found to be independent predictors of survival including: T stage, Karnofsky performance status, N stage, age, total radiation dose to the primary, and Hgb level. Independent predictors of locoregional control included T stage, Karnofsky performance status, N stage, radiation dose, and Hgb level. The only variables which predicted for the development of late RT complications were gender (p = 0.0109) and age (p = 0.0167). These findings were consistent regardless of whether Hgb level was considered a dichotomous or continuous variable. CONCLUSION: Low Hgb levels are associated with a statistically significant reduction in survival and an increase in locoregional failure in this large prospective study of patients with advanced head and neck cancer. Hgb level should be considered as a stratification variable in subsequent studies of head and neck cancer. Strategies to increase Hgb prior to RT in patients with head and neck cancer may lead to improved survival and loco-regional control.

Analysis of Variance↗
PubMed1998

Rapidly alternating chemotherapy and radiotherapy instead of cystectomy for the treatment of muscle-invasive carcinoma of the urinary bladder: long term results of a pilot study.

BACKGROUND: The authors studied rapidly alternating chemotherapy and radiotherapy as the initial treatment for patients with muscle-invasive transitional cell carcinomas of the urinary bladder whose advanced age and lack of strength precluded cystectomy. METHODS: Twenty-one patients with T2 (28%) or T3 (72%) NXM0 carcinomas were treated by transurethral resection followed by chemoradiotherapy. Their median age was 73 years. The chemotherapy (consisting of methotrexate, vinblastine, doxorubicin, and cisplatin) was given during Weeks 1, 4 and 7. Radiotherapy (1.8-2 Gray [Gy] twice a day, to a total dose of 18-20 Gy per week) was given during Weeks 2, 5 and 8, for a final dose of 40 Gy to the pelvis plus 14-20 Gy boost to the affected bladder. RESULTS: There was 1 treatment-related death (5% of patients), but otherwise the acute toxicity was relatively mild. Cystoscopy 1 month after chemoradiotherapy did not reveal invasive cancer in any patient. Subsequent cystoscopies detected recurrent invasive cancer in 3 patients after 30, 44, and 82 months, respectively. The observed survival rate after 5 years was 37%, the cause specific survival rate was 63%, the metastasis free rate was 71%, and the local control rate was 80%. Eighty-four percent of patients had normal bladder function. CONCLUSIONS: Transurethral resection plus chemoradiotherapy was successful in preserving bladder function in the majority of the patients. The survival and progression free rates compared favorably with what has been reported recently after radical cystectomy and chemotherapy, and they add to the growing body of evidence that chemoradiotherapy might be a safe, effective alternative to cystectomy for many patients with muscle-invasive carcinoma of the urinary bladder.

Aged↗
PubMed1998

Close or positive margins after surgical resection for the head and neck cancer patient: the addition of brachytherapy improves local control.

PURPOSE: Microscopically positive or close margins after surgical resection results in an approximately 21-26% local failure rate despite excellent postoperative external radiation therapy. We sought to demonstrate improved local control in head and neck cancer patients who had a resection with curative intent, and had unexpected, microscopically positive or close surgical margins. METHODS AND MATERIALS: Twenty-nine patients with microscopically close or positive margins after curative surgery were given definitive, adjuvant external radiation therapy and 125I brachytherapy. All 29 patients had squamous cell cancer and tonsil was the most common subsite within the head and neck region. After external radiation therapy and thorough discussions with the attending surgeon and pathologists, the slides, gross specimens, and appropriate radiographs were reviewed and a target volume was determined. The target volume was the region of the margin in question and varied in size based on the surgery and pathologic results. Once the target volume was identified the patient was taken back to the operating room for insertion of 125I seeds. Activity implanted (range 2.9-21.5 millicuries) was designed to administer a cumulative lifetime dose of 120-160 Gy. RESULTS: Twenty-nine patients were followed for a median of 26 months (range 5-86 months). Two-year actuarial local control was 92%. CONCLUSION: 125I, after external radiation therapy, is an excellent method to improve local control in the subset of patients with unexpectedly unsatisfactory margins.

Brachytherapy↗
PubMed1996

Radiation therapy of breast carcinoma: confirmation of prescription dose using diodes.

PURPOSE: To quantitate the dose delivered during tangential breast radiation therapy and measure the scatter dose to the contralateral breast for three different breast setup techniques. METHODS AND MATERIALS: A commercial semiconductor diode system is used for dose measurements. The diode characteristics were studied by comparing the diode response against a standard ionization chamber response in a reference configuration. In vivo dose measurements on 11 patients undergoing tangential breast radiation therapy with 6 MV photons were performed. Medial and lateral field entrance and exit doses were measured and compared with the expected values from the treatment planning system. Scatter doses to the contralateral breast for three breast setup techniques were measured and documented as a function of distance from the field edge and various beam modifiers commonly used in breast radiation therapy. RESULTS: The diodes used in this study exhibited excellent linearity, dose reproducibility, and minimal anisotropy. The in-phantom measurements resulted in dose accuracy within +/- 1.5%. Dose measurements on patients resulted in standard deviations of 1.2 and 2.3% for the medial entrance and exit doses and 1.7 and 2.2% for the lateral entrance and exit doses, respectively. In patients, the scatter doses to the opposite breast at a 5 cm perpendicular distance from the medial field edge resulted in cumulative scatter doses of 2.47 to 5.30 Gy from the tangential fields and an additional 0.50 Gy from the supraclavicular or axillary field, if included. CONCLUSION: Quantitative verification of the prescribed daily dose is important in breast radiation therapy to ensure precision in patient setup and accuracy in dose delivery. Diodes provide a convenient way of real-time patient dose verification and are easy to use by the therapists.

Breast Neoplasms↗