Lawrence B. Marks
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Research Subjects
Lawrence B. Marks has a total of 55 co-authors. Here are the top co-authors by number of shared publications:
Donna R. Hollis
Department of Pulmonary, Allergy, and Critical Care, Duke University Medical Center, Durham, NC
3 shared publicationsElizabeth S. Evans
Department of Radiation Oncology, Duke University Medical Center, Durham, NC
2 shared publicationsJingfang Mao
Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA
2 shared publicationsJunan Zhang
Department of Radiation Oncology, Duke University Medical Center, Durham, NC
2 shared publicationsKim L. Light
2 shared publications- Lukasz M. Mazur
Deparmtent of Radiation Oncology - University of North Carolina at Chapel Hill, Chapel Hill, NC
2 shared publications
Latest Publications
- 1 December 2012
- Published by American Society of Clinical Oncology (ASCO) in Journal of Clinical Oncology
- Vol. 30 (34) , 245
Quantification of physician workload for radiotherapy planning, and possible associations with performance.
245 Background: Workload is a hypothetical construct representing the overall human cost incurred during a task. Across disciplines, the NASA Task Load Index (TLX) has been used as a subjective measure of workload. It quantifies six dimensions of work (mental, physical, and temporal demands, frustration, effort, and performance) on a scale of 1-100 scale, with scores >55 (i.e. overworked) associated with lesser performance. We herein quantify differences in physician workload for planning a relatively “simple” (palliative 2 field opposed lateral brain) versus relatively “complex” (curative 4 field pancreas) case. Further, we explore the association between workload and performance to define TLX levels where performance could be expected to decline. Methods: Nine physicians planned two cases, each case involving three tasks (i.e., task 1 - review written patient medical records; task 2 - review diagnostic images and design of treatment fields; and task 3 - review and approval of the treatment plan). After completing each case, TLX scores of each case/task was collected. Differences in workload between cases/tasks were assessed via ANOVA. The association between workload and performance (assessed using time-to-task completion and self-assessments) was assessed via Pearson’s correlation test. Results: 54 TLX workload and performance assessments were obtained. Workloads for the simple brain case/tasks averaged 41-48, versus 62-69 for the complex pancreas case/tasks (p0.1). There was a correlation between TLX scores and time-to-complete (r=0.54, p 55, which is consistent with findings from other industries. Thus, we propose workload assessment (via TLX) to be considered as an independent quality measure to assess the quality assurance (QA) of processes used to deliver radiation therapy.
- 1 December 2012
- Published by American Society of Clinical Oncology (ASCO) in Journal of Clinical Oncology
- Vol. 30 (34) , 245
Quantification of physician workload for radiotherapy planning, and possible associations with performance.
245 Background: Workload is a hypothetical construct representing the overall human cost incurred during a task. Across disciplines, the NASA Task Load Index (TLX) has been used as a subjective measure of workload. It quantifies six dimensions of work (mental, physical, and temporal demands, frustration, effort, and performance) on a scale of 1-100 scale, with scores >55 (i.e. overworked) associated with lesser performance. We herein quantify differences in physician workload for planning a relatively “simple” (palliative 2 field opposed lateral brain) versus relatively “complex” (curative 4 field pancreas) case. Further, we explore the association between workload and performance to define TLX levels where performance could be expected to decline. Methods: Nine physicians planned two cases, each case involving three tasks (i.e., task 1 - review written patient medical records; task 2 - review diagnostic images and design of treatment fields; and task 3 - review and approval of the treatment plan). After completing each case, TLX scores of each case/task was collected. Differences in workload between cases/tasks were assessed via ANOVA. The association between workload and performance (assessed using time-to-task completion and self-assessments) was assessed via Pearson’s correlation test. Results: 54 TLX workload and performance assessments were obtained. Workloads for the simple brain case/tasks averaged 41-48, versus 62-69 for the complex pancreas case/tasks (p0.1). There was a correlation between TLX scores and time-to-complete (r=0.54, p 55, which is consistent with findings from other industries. Thus, we propose workload assessment (via TLX) to be considered as an independent quality measure to assess the quality assurance (QA) of processes used to deliver radiation therapy.
- 1 January 2011
- Vol. 25 (1) , 38-43, 46
How long have I had my cancer, doctor? Estimating tumor age via Collins' law.
To estimate the"age" of cancers at the time of diagnosis, we reviewed data on the "time to local/regional recurrence" (LRF) following initial surgical resection for three common cancers, then applied a modified version of Collins' law. We conducted a systematic review of English medical literature to identify studies reporting LRF rates, over time, following surgery alone for breast, lung, or colorectal cancer. Patients who received radiation/hormones/chemotherapy were excluded since these therapies may alter tumor growth kinetics after surgery. For each disease, data were considered in three ways: 1) absolute cumulative LRF rate over time; 2) percentage of LRFs manifest over time (to facilitate comparisons between studies with different absolute magnitudes of LRFs); and 3) weighted average of the percentage of LRFs manifest over time. For breast cancer (based on data from 3043 patients from 5 studies), we found that the median time to LRF was 2.7 years. For lung cancer (based on data from 1190 patients from 4 studies), the median time to LRF was 1.5 years. For rectal cancer (based on data from 3334 patients from 10 studies), the median time to LRF was 1.5 years. Based on Collins' law, the distribution of time to LRF suggests that the age of most of the solid tumors studied was 3 to 6 years.
- 1 January 2011
- Vol. 25 (1) , 38-43, 46
How long have I had my cancer, doctor? Estimating tumor age via Collins' law.
To estimate the"age" of cancers at the time of diagnosis, we reviewed data on the "time to local/regional recurrence" (LRF) following initial surgical resection for three common cancers, then applied a modified version of Collins' law. We conducted a systematic review of English medical literature to identify studies reporting LRF rates, over time, following surgery alone for breast, lung, or colorectal cancer. Patients who received radiation/hormones/chemotherapy were excluded since these therapies may alter tumor growth kinetics after surgery. For each disease, data were considered in three ways: 1) absolute cumulative LRF rate over time; 2) percentage of LRFs manifest over time (to facilitate comparisons between studies with different absolute magnitudes of LRFs); and 3) weighted average of the percentage of LRFs manifest over time. For breast cancer (based on data from 3043 patients from 5 studies), we found that the median time to LRF was 2.7 years. For lung cancer (based on data from 1190 patients from 4 studies), the median time to LRF was 1.5 years. For rectal cancer (based on data from 3334 patients from 10 studies), the median time to LRF was 1.5 years. Based on Collins' law, the distribution of time to LRF suggests that the age of most of the solid tumors studied was 3 to 6 years.
- 1 December 2007
- Published by Elsevier in International Journal of Radiation Oncology - Biology - Physics (IJROBP)
- Vol. 69 (5) , 1579-1586
The Impact of Advanced Technologies on Treatment Deviations in Radiation Treatment Delivery
- 1 December 2007
- Published by Elsevier in International Journal of Radiation Oncology - Biology - Physics (IJROBP)
- Vol. 69 (5) , 1579-1586
The Impact of Advanced Technologies on Treatment Deviations in Radiation Treatment Delivery
- 1 September 2007
- Published by Elsevier in International Journal of Radiation Oncology - Biology - Physics (IJROBP)
- Vol. 69 (1) , 4-12
Challenges in the Clinical Application of Advanced Technologies to Reduce Radiation-Associated Normal Tissue Injury
- 1 September 2007
- Published by Elsevier in International Journal of Radiation Oncology - Biology - Physics (IJROBP)
- Vol. 69 (1) , 4-12
Challenges in the Clinical Application of Advanced Technologies to Reduce Radiation-Associated Normal Tissue Injury
- 1 March 2007
- Published by Elsevier in International Journal of Radiation Oncology - Biology - Physics (IJROBP)
- Vol. 67 (3) , 759-767
Updated assessment of the six-minute walk test as predictor of acute radiation-induced pneumonitis
- 1 March 2007
- Published by Elsevier in International Journal of Radiation Oncology - Biology - Physics (IJROBP)
- Vol. 67 (3) , 759-767
Updated assessment of the six-minute walk test as predictor of acute radiation-induced pneumonitis
- 1 November 2006
- Published by Elsevier in International Journal of Radiation Oncology - Biology - Physics (IJROBP)
- Vol. 66 (4) , 1125-1134
Impact of patient-specific factors, irradiated left ventricular volume, and treatment set-up errors on the development of myocardial perfusion defects after radiation therapy for left-sided breast cancer
- 1 November 2006
- Published by Elsevier in International Journal of Radiation Oncology - Biology - Physics (IJROBP)
- Vol. 66 (4) , 1125-1134
Impact of patient-specific factors, irradiated left ventricular volume, and treatment set-up errors on the development of myocardial perfusion defects after radiation therapy for left-sided breast cancer
- 1 September 2004
- Vol. 18 (10) , 1289
Comparing radical prostatectomy and brachytherapy for localized prostate cancer.
Radical prostatectomy and ultrasound-guided transperineal brachytherapy are both commonly used for the treatment of localized prostate cancer. No randomized trials are available to compare these modalities. Therefore, the physician must rely on institutional reports of results to determine which therapy is most effective. While some investigators have concluded that both therapies are effective, others have concluded that radical prostatectomy should remain the gold standard for the treatment of this disease. This article reviews the major series available for both treatments and discusses the major controversies involved in making these comparisons. The data indicate that for low-risk disease, both treatments are effective, controlling disease in over 80% of the cases, with no evidence to support the use of one treatment over the other. Similarly, for intermediate-risk disease, the conclusion that one treatment is superior to the other cannot be drawn. Brachytherapy should be performed in conjunction with external-beam radiation therapy in this group of patients. For patients with high-risk disease, neither treatment consistently achieves biochemical control rates above 50%. Although radical prostatectomy and/or brachytherapy may play a role in the care of high-risk patients in the future, external-beam radiation therapy in combination with androgen deprivation has the best track record to date.
- 1 September 2004
- Vol. 18 (10) , 1289
Comparing radical prostatectomy and brachytherapy for localized prostate cancer.
Radical prostatectomy and ultrasound-guided transperineal brachytherapy are both commonly used for the treatment of localized prostate cancer. No randomized trials are available to compare these modalities. Therefore, the physician must rely on institutional reports of results to determine which therapy is most effective. While some investigators have concluded that both therapies are effective, others have concluded that radical prostatectomy should remain the gold standard for the treatment of this disease. This article reviews the major series available for both treatments and discusses the major controversies involved in making these comparisons. The data indicate that for low-risk disease, both treatments are effective, controlling disease in over 80% of the cases, with no evidence to support the use of one treatment over the other. Similarly, for intermediate-risk disease, the conclusion that one treatment is superior to the other cannot be drawn. Brachytherapy should be performed in conjunction with external-beam radiation therapy in this group of patients. For patients with high-risk disease, neither treatment consistently achieves biochemical control rates above 50%. Although radical prostatectomy and/or brachytherapy may play a role in the care of high-risk patients in the future, external-beam radiation therapy in combination with androgen deprivation has the best track record to date.