Lawrence B. Marks, MD | Authors

WHITE MEMORIAL MEDICAL CENTER

1720 E CESAR E CHAVEZ AVE

Articles

How Long Have I Had My Cancer, Doctor?

January 15, 2011

“How long have I had this cancer, Doctor?” This is a question that patients frequently ask their oncologist.

Radiation-Induced Lung Injury: Assessment, Management, and Prevention

January 01, 2008

Radiation therapy (RT) is an important treatment modality for multiple thoracic malignancies. Incidental irradiation of the lungs, which are particularly susceptible to injury, is unavoidable and often dose-limiting. The most radiosensitive subunit of the lung is the alveolar/capillary complex, and RT-induced lung injury is often described as diffuse alveolar damage. Reactive oxygen species generated by RT are directly toxic to parenchymal cells and initiate a cascade of molecular events that alter the cytokine milieu of the microenvironment, creating a self-sustaining cycle of inflammation and chronic oxidative stress. Replacement of normal lung parenchyma by fibrosis is the culminating event. Depending on the dose and volume of lung irradiated, acute radiation pneumonitis may develop, characterized by dry cough and dyspnea. Fibrosis of the lung, which can also cause dyspnea, is the late complication. Imaging studies and pulmonary function tests can be used to quantify the extent of lung injury. While strict dose-volume constraints to minimize the risk of injury are difficult to impose, substantial data support some general guidelines. New modalities such as intensity-modulated radiation therapy and stereotactic body radiation therapy provide new treatment options but also pose new challenges in safely delivering thoracic RT.

Association Between the Rates of Synchronous and Metachronous Metastases: Analysis of SEER Data

June 01, 2007

Patients with cancer are usually staged based on the presence of detectable regional and/or distant disease. However, staging is inexact and cM0 patients may have microscopic metastases (cM0pM1) that later cause relapse and death. Since the clinical tools used to stage patients are fairly similar for different tumors, the ratio of the rates of metachronous to synchronous metastases should be similar for different tumors (hypothesis #1). Improvements in diagnostic tools should have caused the ratio of metachronous-to-synchronous metastases to have decreased over time (hypothesis #2). Finally, the fraction of patients with either metachronous or synchronous metastases should have declined over time due to increased screening and earlier diagnoses (hypothesis #3). To test these hypotheses, Surveillance, Epidemiology, and End Results (SEER) data from 1973-1998 were analyzed for 19 solid tumors. A linear relationship was seen between the rates of metachronous and synchronous metastases, with modestly strong correlation coefficients, consistent with hypothesis #1. Over time, changes in staging methods have not significantly altered the ratio of metachronous/synchronous metastases, contrary to hypothesis #2. Also over time, a decrease in the number of patients with metastases was found, consistent with hypothesis #3. Therefore, the rate of anticipated metachronous metastases can be estimated from the rate of clinically evident metastases at presentation. Changes in screening/staging of disease over time may have reduced the overall fraction of patients with metastases.

Stage III Lung Cancer: Two or Three Modalities?

September 01, 2006

Lung cancer is the leading cause of cancer mortality in the United States. A significant number of patients present with disease involving mediastinal lymph nodes. As survival after surgery alone for stage III disease is poor, radiation therapy and chemotherapy have been evaluated in the neoadjuvant and adjuvant settings to improve outcomes. The benefit of adjuvant chemotherapy in the subgroup of patients with N2 disease is uncertain. Small randomized trials enrolling patients with stage III disease have shown a benefit of neoadjuvant chemotherapy over surgery alone. Whether neoadjuvant chemotherapy is superior to adjuvant chemotherapy is under investigation. Furthermore, whether neoadjuvant chemoradiotherapy is superior to neoadjuvant chemotherapy is controversial, and few randomized studies comparing these approaches have been reported. Nevertheless, neoadjuvant chemoradiotherapy appears to be associated with higher rates of resection, higher rates of clearance of mediastinal nodal disease, and better local/regional control. The use of postoperative radiation therapy (PORT) has declined since the publication of the 1998 meta-analysis suggested a detriment in survival with this strategy. However, radiation techniques are improving and emerging data support the use of carefully delivered PORT. Finally, it remains unclear whether surgical resection offers an advantage over definitive chemoradiotherapy alone for stage III disease. In summary, locally advanced NSCLC remains a formidable challenge with few cures, and optimal treatment requires the careful use of surgery, chemotherapy, and radiation therapy.

Comparing Radical Prostatectomy and Brachytherapy for Localized Prostate Cancer

September 01, 2004

Radical prostatectomy and ultrasound-guided transperinealbrachytherapy are both commonly used for the treatment of localizedprostate cancer. No randomized trials are available to compare thesemodalities. Therefore, the physician must rely on institutional reportsof results to determine which therapy is most effective. While some investigatorshave concluded that both therapies are effective, others haveconcluded that radical prostatectomy should remain the gold standardfor the treatment of this disease. This article reviews the major seriesavailable for both treatments and discusses the major controversiesinvolved in making these comparisons. The data indicate that for lowriskdisease, both treatments are effective, controlling disease in over80% of the cases, with no evidence to support the use of one treatmentover the other. Similarly, for intermediate-risk disease, the conclusionthat one treatment is superior to the other cannot be drawn. Brachytherapyshould be performed in conjunction with external-beam radiationtherapy in this group of patients. For patients with high-risk disease,neither treatment consistently achieves biochemical control rates above50%. Although radical prostatectomy and/or brachytherapy may playa role in the care of high-risk patients in the future, external-beamradiation therapy in combination with androgen deprivation has thebest track record to date.

Routine 3D Treatment Planning: Opportunities, Challenges, and Hazards

August 01, 2000

Three-dimensional (3D) treatment planning refers to the use of software and hardware tools to design and implement more accurate and conformal radiation therapy. This is a major advance in oncology that should lead to

Mounting Evidence for Postmastectomy Locoregional Radiation Therapy

August 01, 1999

Postmastectomy locoregional radiation therapy markedly reduces the risk of locoregional recurrence. Several randomized trials, including two recently updated studies with 10- to 15-year follow-up, demonstrate an

Lumpectomy With and Without Radiation for Early-Stage Breast Cancer and DCIS

September 01, 1997

Breast-conserving therapy with lumpectomy and breast irradiation is an accepted standard treatment for patients with early-stage invasive breast cancer or ductal carcinoma in situ (DCIS). For both diseases, investigators have tried to identify subgroups of patients who can be "safely" treated with lumpectomy without radiation. Some data suggest that it may be reasonable to omit radiation therapy in patients with small, low-grade invasive or noninvasive tumors and/or in "elderly" patients. Additional studies are needed to better identify criteria to prospectively select appropriate patients for treatment with lumpectomy alone. [ONCOLOGY 11(9):1361-1374, 1997]