Biomedical subjects

Samir Narayan

Publications and source records attributed to Samir Narayan.

9 recordsLinked to original sources

PubMed2006

Use of benchmark dose-volume histograms for selection of the optimal technique between three-dimensional conformal radiation therapy and intensity-modulated radiation therapy in prostate cancer.

PURPOSE: The aim of this study was to develop and validate our own benchmark dose-volume histograms (DVHs) of bladder and rectum for both conventional three-dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT), and to evaluate quantitatively the benefits of using IMRT vs. 3D-CRT in treating localized prostate cancer. METHODS AND MATERIALS: During the implementation of IMRT for prostate cancer, our policy was to plan each patient with both 3D-CRT and IMRT. This study included 31 patients with T1b to T2c localized prostate cancer, for whom we completed double-planning using both 3D-CRT and IMRT techniques. The target volumes included prostate, either with or without proximal seminal vesicles. Bladder and rectum DVH data were summarized to obtain an average DVH for each technique and then compared using two-tailed paired t test analysis. RESULTS: For 3D-CRT our bladder doses were as follows: mean 28.8 Gy, v60 16.4%, v70 10.9%; rectal doses were: mean 39.3 Gy, v60 21.8%, v70 13.6%. IMRT plans resulted in similar mean dose values: bladder 26.4 Gy, rectum 34.9 Gy, but lower values of v70 for the bladder (7.8%) and rectum (9.3%). These benchmark DVHs have resulted in a critical evaluation of our 3D-CRT techniques over time. CONCLUSION: Our institution has developed benchmark DVHs for bladder and rectum based on our clinical experience with 3D-CRT and IMRT. We use these standards as well as differences in individual cases to make decisions on whether patients may benefit from IMRT treatment rather than 3D-CRT.

Adult↗

PubMed2006

Multimodality therapy for Pancoast tumor.

The management of Pancoast tumors has challenged surgeons and radiation and medical oncologists over several decades. Retrospective studies have raised a greater awareness of the importance of positive N2 lymph nodes in terms of prognosis and treatment decision making. While patients with positive N2 lymph nodes have generally been excluded from trials of preoperative chemoradiation for superior sulcus tumors, the potential of surgery for these patients is still being evaluated. The role of PET for initial staging as well as for assessment of disease response to induction therapy continues to evolve. The use of combined treatment modalities has enhanced the progress in successfully treating Pancoast tumors. The historical data showing improved results with a combination of surgery and radiation compared with surgery alone for patients with positive N2 nodes provides the basis for several important clinical trials that integrate the use of chemotherapy into the treatment paradigm. The Southwest Oncology Group and Japanese Clinical Oncology Group have shown dramatic improvements in complete resection rates following a neoadjuvant course of combined chemotherapy and radiation therapy compared with historical series. We discuss relevant ongoing clinical trials that include consolidative taxane-based chemotherapy and the role of prophylactic cranial irradiation in complete responders. Future potential areas of investigation, including the role of surgery for patients with N2-positive disease and the use of imaging to assess response after induction therapy, are discussed.

Combined Modality Therapy↗

PubMed2005

Integration of novel therapeutics into combined modality therapy of locally advanced non-small cell lung cancer.

Novel therapeutic agents (NTA) directed against a wide array of newly described molecular targets are now entering clinical investigation, many in the treatment of non-small cell lung cancer (NSCLC). The great majority of these clinical trials have been directed toward patients with advanced stage (metastatic) disease. More recently, study of NTAs has turned toward earlier-stage disease. Locally advanced, or stage III, NSCLC represents a large and heterogeneous group of patients and several clinically distinct substages. During the last 15 years, randomized clinical trials have shown improved survival with sequential chemoradiation compared with radiation alone and, more recently, the superiority of concurrent versus sequential chemoradiation. As NTAs have increasingly shown clinical activity against NSCLC, questions of how to incorporate them into clinical trials in stage III disease, whether they should be given together with radiotherapy, substituting for chemotherapy, or whether they should be added to current chemoradiation strategies, all remain as issues. Here, we describe conceptual issues, preclinical rationale, and ongoing or planned clinical trials incorporating NTAs into current treatment paradigms for unresectable stage III NSCLC.

Antineoplastic Agents↗

PubMed2005

The use of intensity-modulated radiation therapy in the treatment of oropharyngeal carcinoma.

PURPOSE OF REVIEW: The management of oropharyngeal cancers continues to evolve. Due to the functional consequences of surgery, organ preservation strategies with radiation combined with chemotherapy have been developed. Newer strategies to diminish the acute and late toxicities and improve the functional outcome of organ preservation strategies are being developed. Intensity-modulated radiation therapy is a relatively new, advanced form of radiation therapy that is being studied in an effort to improve local control rates and minimize the late effects of treatment. RECENT FINDINGS: Several recent studies have further supported the role for radiation therapy and chemotherapy as part of organ preservation strategies for cancers of the oropharynx. With the intensification of treatment, however, toxicities and functional impairment occur and have not been well documented in the past. Several recent studies report on the toxicities of traditional treatment methods. In addition, data show that intensity-modulated radiation therapy may be superior in terms of limiting toxicity compared with standard radiation therapy techniques. The integration of intensity-modulated radiation therapy with chemotherapeutic and radioprotective agents to further improve the therapeutic window for radiation therapy is being actively pursued. SUMMARY: This paper reviews recent advances in radiotherapy for oropharynx cancer and the use of intensity-modulated radiation therapy.

Carcinoma, Squamous Cell↗

PubMed2004

An electronic application for rapidly calculating Charlson comorbidity score.

BACKGROUND: Uncertainty regarding comorbid illness, and ability to tolerate aggressive therapy has led to minimal enrollment of elderly cancer patients into clinical trials and often substandard treatment. Increasingly, comorbid illness scales have proven useful in identifying subgroups of elderly patients who are more likely to tolerate and benefit from aggressive therapy. Unfortunately, the use of such scales has yet to be widely integrated into either clinical practice or clinical trials research. METHODS: This article reviews evidence for the validity of the Charlson Comorbidity Index (CCI) in oncology and provides a Microsoft Excel (MS Excel) Macro for the rapid and accurate calculation of CCI score. The interaction of comorbidity and malignant disease and the validation of the Charlson Index in oncology are discussed. RESULTS: The CCI score is based on one year mortality data from internal medicine patients admitted to an inpatient setting and is the most widely used comorbidity index in oncology. An MS Excel Macro file was constructed for calculating the CCI score using Microsoft Visual Basic. The Macro is provided for download and dissemination. The CCI has been widely used and validated throughout the oncology literature and has demonstrated utility for most major cancers. The MS Excel CCI Macro provides a rapid method for calculating CCI score with or without age adjustments. The calculator removes difficulty in score calculation as a limitation for integration of the CCI into clinical research. The simple nature of the MS Excel CCI Macro and the CCI itself makes it ideal for integration into emerging electronic medical records systems. CONCLUSIONS: The increasing elderly population and concurrent increase in oncologic disease has made understanding the interaction between age and comorbid illness on life expectancy increasingly important. The MS Excel CCI Macro provides a means of increasing the use of the CCI scale in clinical research with the ultimate goal of improving determination of optimal treatments for elderly cancer patients.

Aged↗

PubMed2004

Results following treatment to doses of 92.4 or 102.9 Gy on a phase I dose escalation study for non-small cell lung cancer.

BACKGROUND AND PURPOSE: The University of Michigan lung dose escalation study has increased the dose of external beam radiation for non-small cell lung cancer based on the volume of normal lung irradiated. The results of patients treated to either 92.4 or 102.9 Gy are reported. MATERIALS AND METHODS: Seventeen patients have completed treatment to 92.4 or 102.9 Gy and have been followed for at least 6 months. The treatment planning goal was to minimize the effective volume (V(eff)) of total lung irradiated as computed using the Kutcher-Burman DVH reduction scheme. Dose was escalated independently within each of five V(eff) bins. Toxicity, freedom from local progression (FFLP), overall survival (OS) and cause specific survival (CSS) are reported. RESULTS: Thirteen patients were Stage I, one was Stage II and three were Stage III. V(eff) ranged from 0.06 to 0.21. The median pretreatment FEV(1) was 1.24 L or 44% of predicted. Median follow-up for survivors was 37.9 months. No patient had significant pulmonary toxicity. One patient each had grades 2 and 3 esophagitis. Median percent change in FEV1 was -11%. Two- and three-year actuarial FFLP and OS rates for the entire group were 68 and 58% and 51 and 26%, respectively. For Stage I patients, the 2 and 3 year FFLP, OS and CSS rates were 82 and 68%, 54 and 33%, 76 and 48% respectively. CONCLUSIONS: These results suggest that doses of radiation of 92.4 and 102.9 Gy can be delivered safely to limited lung volumes with minimal toxicity.

Aged↗

PubMed2003

Preliminary visual outcomes after three-dimensional conformal radiation therapy for optic nerve sheath meningioma.

PURPOSE: We assessed visual outcomes, local control, and toxicity associated with three-dimensional conformal radiation therapy (3D-CRT) for primary optic nerve sheath meningiomas (ONSM). METHODS: Twenty-three patients diagnosed with ONSM were evaluated at the University of Michigan between 1986 and 2001. Fourteen patients were treated with 3D-CRT. Detailed pre- and postradiation treatment ophthalmologic examinations and MRIs were performed on all patients. Clinically significant visual acuity change was defined as a >or=three line change on the Snellen chart. Mean deviation change of >or=three decibels was defined as a clinically significant visual field change. Radiographic progression was defined as any increase in size on MRI. Acute and late toxicity was scored according to RTOG criteria. RESULTS: Median follow-up was 51.3 months. Five patients had a clinically significant improvement in visual acuity. Seven had stable acuity, and only 2 worsened. Nine patients had clinically significant visual field improvement. One patient developed early radiation retinopathy, 1 experienced orbital pain, 1 developed dry eye, and 2 developed iritis. No patient has required additional treatment, and none have demonstrated radiographic progression. CONCLUSION: 3D-CRT is effective in controlling tumor growth while improving or preserving vision in most patients with optic nerve sheath meningiomas.

Adolescent↗

PubMed2003

Combined modality treatment for prostate cancer: role of chemotherapy.

Chemotherapy for prostate cancer currently has an established role in the treatment of hormone-refractory prostate cancer. There is strong evidence that combined modality treatment with androgen ablation in addition to radiotherapy provides a benefit above and beyond radiotherapy alone in patients with a poor prognosis, perhaps because of an effect of androgen ablation on subclinical distant disease. There are currently several clinical trials investigating whether the addition of chemotherapy with known efficacy in the hormone-refractory setting can provide a survival advantage when used adjuvantly. The role of chemotherapy for patients with nonmetastatic, hormone-naive prostate cancer will be discussed.

Androgen Antagonists↗

PubMed2003

Chemotherapy for localized, high-risk prostate cancer.

Chemotherapy for prostate cancer currently has an established role in the treatment of hormone refractory prostate cancer. In addition, there is strong evidence that androgen ablation in addition to radiotherapy provides a benefit above and beyond radiotherapy alone in patients with a poor prognosis, perhaps because of an effect of androgen ablation on subclinical distant disease. There are currently several clinical trials that are investigating whether the addition of chemotherapy with known efficacy in the hormone-refractory setting can provide a survival advantage when used adjunctly. The role of chemotherapy in the nonmetastatic prostate, hormone-naïve prostate cancer patient will be discussed.

Androgen Antagonists↗