Stereotactic body radiation therapy for inoperable early stage lung cancer

Stereotactic ablative radiation therapy for primary lung tumors

Stereotactic ablative radiotherapy, also known as stereotactic body radiation therapy, has been developed as an innovative therapy for stage I non-small cell lung cancer and has now emerged as a standard treatment option for medically inoperable patients through careful analysis utilizing prospective, multi-institutional trials. This article reviews and updates the evidence for use of stereotactic ablative radiotherapy in medically inoperable patients with stage I lung cancer, its extension of use to medically operable patients, and the toxicities associated with this emerging technique.

Radiobiological rationale and clinical implications of hypofractionated radiation therapy

Recent clinical trials of hypofractionated radiation treatment have provided critical insights into the safety and efficacy of hypofractionation. However, there remains much controversy in the field, both at the level of clinical practice and in our understanding of the underlying radiobiological mechanisms. In this article, we review the clinical literature on hypofractionated radiation treatment for breast, prostate, and other malignancies. We highlight several ongoing clinical trials that compare outcomes of a hypofractionated approach versus those obtained with a conventional approach. Lastly, we outline some of the preclinical and clinical evidence that argue in favor of differential radiobiological mechanisms underlying hypofractionated radiation treatment. Emerging data from the ongoing studies will help to better define and guide the rational use of hypofractionation in future years.

Phase I dose-escalation study of stereotactic body radiation therapy for low- and intermediate-risk prostate cancer

PURPOSE

To evaluate the tolerability of escalating doses of stereotactic body radiation therapy in the treatment of localized prostate cancer.

PATIENTS AND METHODS

Eligible patients included those with Gleason score 2 to 6 with prostate-specific antigen (PSA) ≤ 20, Gleason score 7 with PSA ≤ 15, ≤ T2b, prostate size ≤ 60 cm(3), and American Urological Association (AUA) score ≤ 15. Pretreatment preparation required an enema and placement of a rectal balloon. Dose-limiting toxicity (DLT) was defined as grade 3 or worse GI/genitourinary (GU) toxicity by Common Terminology Criteria of Adverse Events (version 3). Patients completed quality-of-life questionnaires at defined intervals.

RESULTS

Groups of 15 patients received 45 Gy, 47.5 Gy, and 50 Gy in five fractions (45 total patients). The median follow-up is 30 months (range, 3 to 36 months), 18 months (range, 0 to 30 months), and 12 months (range, 3 to 18 months) for the 45 Gy, 47.5 Gy, and 50 Gy groups, respectively. For all patients, GI grade ≥ 2 and grade ≥ 3 toxicity occurred in 18% and 2%, respectively, and GU grade ≥ 2 and grade ≥ 3 toxicity occurred in 31% and 4%, respectively. Mean AUA scores increased significantly from baseline in the 47.5-Gy dose level (P = .002) as compared with the other dose levels, where mean values returned to baseline. Rectal quality-of-life scores (Expanded Prostate Cancer Index Composite) fell from baseline up to 12 months but trended back at 18 months. In all patients, PSA control is 100% by the nadir + 2 ng/mL failure definition.

CONCLUSION

Dose escalation to 50 Gy has been completed without DLT. A multicenter phase II trial is underway treating patients to 50 Gy in five fractions to further evaluate this experimental therapy.

Dosimetric characterization of an image-guided stereotactic small animal irradiator

Small animal irradiation provides an important tool used by preclinical studies to assess and optimize new treatment strategies such as stereotactic ablative radiotherapy. Characterization of radiation beams that are clinically and geometrically scaled for the small animal model is uniquely challenging for orthovoltage energies and minute field sizes. The irradiator employs a commercial x-ray device (XRAD 320, Precision x-ray, Inc.) with a custom collimation system to produce 1-10 mm diameter beams and a 50 mm reference beam. Absolute calibrations were performed using the AAPM TG-61 methodology. Beam's half-value layer (HVL) and timer error were measured with an ionization chamber. Percent depth dose (PDD), output factors (OFs) and off-axis ratios were measured using radiochromic film, a diode and a pinpoint ionization chamber at 19.76 and 24.76 cm source-to-surface distance (SSD). PDD measurements were also compared with Monte Carlo (MC) simulations. In-air and in-water absolute calibrations for the reference 50 mm diameter collimator at 19.76 cm SSD were measured as 20.96 and 20.79 Gy min(-1), respectively, agreeing within 0.8%. The HVL at 250 kVp and 15 mAs was measured to be 0.45 mm Cu. The reference field PDD MC simulation results agree with measured data within 3.5%. PDD data demonstrate typical increased penetration with increasing field size and SSD. For collimators larger than 5 mm in diameter, OFs measured using film, an ion chamber and a diode were within 3% agreement.

Surgical treatment of local recurrence after stereotactic body radiotherapy for primary and metastatic lung cancers

INTRODUCTION

Stereotactic body radiotherapy (SBRT) has been proposed as an alternative to surgery for the treatment of lung cancer. The treatment of local recurrence that occurs after SBRT has not been reported. We present surgical outcomes for local recurrence following SBRT for primary and metastatic lung cancers.

METHODS

Seven of the patients who received SBRT between 2002 and 2008 underwent salvage surgery for local recurrence. These seven patients (two with stage I non-small cell lung cancer and five with metastatic tumors) were operable, although they refused surgery and chose SBRT for the first treatment as a less invasive procedure.

RESULTS

Six of the seven patients underwent lobectomy, and the other patient underwent segmentectomy. None of the seven patients had direct pleural adhesion resulting from SBRT, although, in general, radiation fibrosis occurs after radiotherapy and induces pleural adhesion that makes surgery difficult.

CONCLUSIONS

Our study suggests that SBRT may not be the cause of difficulties encountered during the surgical process, and surgery is a good alternative treatment for local recurrence after SBRT. During follow-up after SBRT, the appearance of tumor regrowth on lung images resembled that of inflammatory changes such as radiation pneumonitis. We suggest that close follow-ups should be mandatory after SBRT.

Stereotactic radiotherapy of primary lung cancer and other targets: results of consultant meeting of the International Atomic Energy Agency

To evaluate the current status of stereotactic body radiotherapy (SBRT) and identify both advantages and disadvantages of its use in developing countries, a meeting composed of consultants of the International Atomic Energy Agency was held in Vienna in November 2006. Owing to continuous developments in the field, the meeting was extended by subsequent discussions and correspondence (2007-2010), which led to the summary presented here. The advantages and disadvantages of SBRT expected to be encountered in developing countries were identified. The definitions, typical treatment courses, and clinical results were presented. Thereafter, minimal methodology/technology requirements for SBRT were evaluated. Finally, characteristics of SBRT for developing countries were recommended. Patients for SBRT should be carefully selected, because single high-dose radiotherapy may cause serious complications in some serial organs at risk. Clinical experiences have been reported in some populations of lung cancer, lung oligometastases, liver cancer, pancreas cancer, and kidney cancer. Despite the disadvantages expected to be experienced in developing countries, SBRT using fewer fractions may be useful in selected patients with various extracranial cancers with favorable outcome and low toxicity.

Stereotactic body radiotherapy for medically inoperable lung cancer: prospective, single-center study of 108 consecutive patients

PURPOSE

To present the results of stereotactic body radiotherapy (SBRT) for medically inoperable patients with Stage I non-small-cell lung cancer (NSCLC) and contrast outcomes in patients with and without a pathologic diagnosis.

METHODS AND MATERIALS

Between December 2004 and October 2008, 108 patients (114 tumors) underwent treatment according to the prospective research ethics board-approved SBRT protocols at our cancer center. Of the 108 patients, 88 (81.5%) had undergone pretreatment whole-body [18F]-fluorodeoxyglucose positron emission tomography/computed tomography. A pathologic diagnosis was unavailable for 33 (28.9%) of the 114 lesions. The SBRT schedules included 48 Gy in 4 fractions or 54-60 Gy in 3 fractions for peripheral lesions and 50-60 Gy in 8-10 fractions for central lesions. Toxicity and radiologic response were assessed at the 3-6-month follow-up visits using conventional criteria.

RESULTS

The mean tumor diameter was 2.4-cm (range, 0.9-5.7). The median follow-up was 19.1 months (range, 1-55.7). The estimated local control rate at 1 and 4 years was 92% (95% confidence interval [CI], 86-97%) and 89% (95% CI, 81-96%). The cause-specific survival rate at 1 and 4 years was 92% (95% CI, 87-98%) and 77% (95% CI, 64-89%), respectively. No statistically significant difference was found in the local, regional, and distant control between patients with and without pathologically confirmed NSCLC. The most common acute toxicity was Grade 1 or 2 fatigue (53 of 108 patients). No toxicities of Grade 4 or greater were identified.

CONCLUSIONS

Lung SBRT for early-stage NSCLC resulted in excellent local control and cause-specific survival with minimal toxicity. The disease-specific outcomes were comparable for patients with and without a pathologic diagnosis. SBRT can be considered an option for selected patients with proven or presumed early-stage NSCLC.

Lung cancer: New biological insights and recent therapeutic advances

Approximately 1.6 million new cases of lung cancer are diagnosed each year throughout the world. In many countries, the mortality related to lung cancer continues to rise. The outcomes for patients with all stages of lung cancer have improved in recent years. The use of systemic therapy in conjunction with local therapy has led to improved cure rates in both resectable and unresectable patient groups. For patients with advanced stage disease, modest but real improvements in overall survival and quality of life have been achieved with systemic chemotherapy. A major focus of research has been the development of molecularly targeted agents and the identification of biomarkers for patient selection. Patients with non-small cell lung cancer with mutations in the epidermal growth factor receptor (EGFR) tyrosine kinase domain achieve response rates of greater than 70% and superior progression-free survival when treated with an EGFR tyrosine kinase inhibitor compared with standard chemotherapy. This has now emerged as the preferred therapeutic approach for the subset of patients with a mutation in exons 19 or 21 of the EGFR. Another promising targeted approach involves the use of an anaplastic lymphoma kinase (ALK) inhibitor in patients with a translocation involving the echinoderm microtubule-associated protein-like 4 (EML4) and -ALK genes. Finally, a paradigm shift in favor of maintenance therapy for patients with advanced stage disease has gained strength from recent data. All of these advances have been made possible by developing a greater understanding of the biology, the discovery of novel anticancer agents, and improved supportive care measures. This article reviews the major strides made in the treatment of lung cancer in the recent past.

A novel respiratory motion compensation strategy combining gated beam delivery and mean target position concept --a compromise between small safety margins and long duty cycles

PURPOSE

To evaluate a novel respiratory motion compensation strategy combining gated beam delivery with the mean target position (MTP) concept for pulmonary stereotactic body radiotherapy (SBRT).

MATERIALS AND METHODS

Four motion compensation strategies were compared for 10 targets with motion amplitudes between 6mm and 31mm: the internal target volume concept (plan(ITV)); the MTP concept where safety margins were adapted based on 4D dose accumulation (plan(MTP)); gated beam delivery without margins for motion compensation (plan(gated)); a novel approach combining gating and the MTP concept (plan(gated&MTP)).

RESULTS

For 5/10 targets with an average motion amplitude of 9mm, the differences in the mean lung dose (MLD) between plan(gated) and plan(MTP) were <10%. For the other 5/10 targets with an average motion amplitude of 19mm, gating with duty cycles between 87.5% and 75% reduced the residual target motion to 12mm on average and 2mm safety margins were sufficient for dosimetric compensation of this residual motion in plan(gated&MTP). Despite significantly shorter duty cycles, plan(gated) reduced the MLD by <10% compared to plan(gated&MTP). The MLD was increased by 18% in plan(MTP) compared to that of plan(gated&MTP).

CONCLUSIONS

For pulmonary targets with motion amplitudes >10-15mm, the combination of gating and the MTP concept allowed small safety margins with simultaneous long duty cycles.

CyberKnife stereotactic ablative radiotherapy for lung tumors

Stereotactic ablative radiotherapy (SABR) has emerged as a promising treatment for early stage non-small cell lung cancer, particularly for patients unable to tolerate surgical resection. High rates of local tumor control have been demonstrated with acceptable toxicity and the practical advantage of a short course of treatment. The CyberKnife image-guided robotic radiosurgery system has unique technical characteristics that make it well suited for SABR of tumors that move with breathing, including lung tumors. We review the qualities of the CyberKnife platform for lung tumor SABR, and provide a summary of clinical data using this system specifically.

Cost-effectiveness analysis of stereotactic body radiotherapy and radiofrequency ablation for medically inoperable, early-stage non-small cell lung cancer

PURPOSE

The standard management of medically inoperable Stage I non-small-cell lung cancer (NSCLC) conventionally has been fractionated three-dimensional conformal radiation therapy (3D-CRT). The relatively poor local control rate and inconvenience associated with this therapy have prompted the development of stereotactic body radiotherapy (SBRT), a technique that delivers very high doses of irradiation typically over 3 to 5 sessions. Radiofrequency ablation (RFA) has also been investigated as a less costly, single-day therapy that thermally ablates small, peripheral tumors. The cost-effectiveness of these three techniques has never been compared.

METHODS AND MATERIALS

We developed a Markov model to describe health states of 65-year-old men with medically inoperable NSCLC after treatment with 3D-CRT, SBRT, and RFA. Given their frail state, patients were assumed to receive supportive care after recurrence. Utility values, recurrence risks, and costs were adapted from the literature. Sensitivity analyses were performed to model uncertainty in these parameters.

RESULTS

The incremental cost-effectiveness ratio for SBRT over 3D-CRT was $6,000/quality-adjusted life-year, and the incremental cost-effectiveness ratio for SBRT over RFA was $14,100/quality-adjusted life-year. One-way sensitivity analysis showed that the results were robust across a range of tumor sizes, patient utility values, and costs. This result was confirmed with probabilistic sensitivity analyses that varied local control rates and utilities.

CONCLUSION

In comparison to 3D-CRT and RFA, SBRT was the most cost-effective treatment for medically inoperable NSCLC over a wide range of treatment and disease assumptions. On the basis of efficacy and cost, SBRT should be the primary treatment approach for this disease.

Initial experience and clinical comparison of two image guidance methods for SBRT treatment: 4DCT versus respiratory-triggered imaging

For Stereotactic Body Radiation Therapy (SBRT) treatment of lung and liver, we quantified the differences between two image guidance methods: 4DCT and ExacTrac respiratory‐triggered imaging. Five different patients with five liver lesions and one lung lesion for a total of 19 SBRT delivered fractions were studied. For the 4DCT method, a manual registration process was used between the 4DCT image sets from initial simulation and treatment day to determine the required daily image‐guided corrections. We also used the ExacTrac respiratory‐triggered imaging capability to verify the target positioning, and calculated the differences in image guidance shifts between these two methods. The mean (standard deviation) of the observed differences in image‐guided shifts between 4DCT and ExacTrac respiratory‐triggered image guidance was left/right (L/R)=0.4(2.0)mm, anterior/posterior (A/P)=1.4(1.7) mm, superior/inferior (S/I)=2.2(2.0) mm, with no difference larger than 5.0 mm in any given direction for any individual case. The largest error occurred in the S/I direction, with a mean of 2.2 mm for the six lesions. This seems reasonable, because respiratory motion and the resulting imaging uncertainties are most pronounced in this S/I direction. Image guidance shifts derived from ExacTrac triggered imaging at two extreme breathing phases (i.e., full exhale vs. full inhale), agreed well (less than 2.0 mm) with each other. In summary, two very promising image guidance methods of 4DCT and ExacTrac respiratory‐triggered imaging were presented and the image guidance shifts were comparable for the patients evaluated in this study.

PACS number: 87.55.ne

Feasibility of helical tomotherapy in stereotactic body radiation therapy for centrally located early stage non‒small-cell lung cancer or lung metastases

PURPOSE

To investigate the ability of helical tomotherapy (HT) to spare critical organs immediately adjacent to the tumor target in stereotactic body radiation therapy (SBRT) for centrally located lung lesions.

METHODS AND MATERIALS

HT SBRT plans for 10 patients with centrally located lesions or lesions immediately adjacent to a critical structure were generated. A total of 70 Gy in 10 fractions was prescribed to the planning target volume (PTV) to satisfy a target volume coverage of ≥95% PTV receiving 70 Gy and an established set of dose constraints for the organs at risk (OARs). Quality assurance (QA) of the HT plans was performed with both ion chamber and film measurements.

RESULTS

The PTV coverage criteria was met with 95% of the PTV receiving 70.68 ± 0.33 Gy for all cases even though the OARs immediately adjacent to the PTV ranged from 0.38 to 0.85 cm away. The mean lung dose (MLD), and V(20) were 7.15 ± 1.44 Gy, and 11.93 ± 3.24 % for the total lung, respectively. The dose parameters of MLD, V(5), V(10), and V(20) for the contralateral lung were significantly lower than those for the ipsilateral lung (p < 0.05). An average dose fall off from the PTV periphery to the edge of the immediately adjacent OAR was 47.6% over an average distance of 4.87 mm. Comparison of calculated and measured doses with the ion chamber showed an average of 1.85% point dose error, whereas an average mean gamma and the area with a gamma larger than 1 of 0.20 and 0.94% were observed, respectively.

CONCLUSION

HT allows the sparing of critical structures immediately adjacent to the tumor target, thus making SBRT for these centrally located lesions feasible.

Quality and safety in stereotactic radiosurgery and stereotactic body radiation therapy: can more be done?

Stereotactic radiosurgery (SRS) has been an effective modality for the treatment of benign and malignant cranial disease for 50 years. Increasingly, the stereotactic approach, ablative doses of radiation delivered in a highly focused manner to a target of interest, is being applied in a number of extracranial disease sites. Stereotactic body radiation therapy (SBRT) holds significant potential for improving tumor control rates across a range of locations and histologies. Both SRS and SBRT require specialized technology, meticulous procedures, and dedicated personnel. Several recent high-profile medical radiation events have generated considerable attention within the media, and serve to remind the profession that close attention to ongoing quality improvement is a fundamental responsibility. The purpose of this manuscript is to provide some recommendations for SRS / SBRT processes and procedures that may be beneficial in understanding and reducing risks inherent to the modalities.

Spine radiosurgery for spinal cord compression: the radiation oncologist's perspective

Metastatic spinal cord compression (MSCC) is a common problem afflicting cancer patients. It affects 5-14% of all patients with cancer, and more than 20,000 cases are diagnosed annually in the United States (1-3). Once diagnosed, it is considered to be a medical emergency, and immediate intervention is required with high-dose corticosteroids and radiotherapy (RT), with or without decompressive surgery. Without therapy, MSCC is a source of significant morbidity and mortality, causing pain, paralysis, incontinence, and an overall decline in quality of life. Even with aggressive therapy, results can often be unsatisfactory. Although most patients will die of their underlying cancer within the first year of the diagnosis of MSCC, up to one-third will survive beyond one year (4-5). Therefore, optimal therapy is required to maintain quality of life.

Stereotactic body radiotherapy (SBRT): Technological innovation and application in gynecologic oncology

OBJECTIVES

Stereotactic body radiotherapy (SBRT) is a novel form of noninvasive, highly conformal radiation treatment that delivers a high dose to tumor. The advantage of the technique resides in its ability to provide a high dose to tumor but spare normal tissues to an extent not previously possible. In this paper we will provide an introduction and review of this technology with regard to its use in gynecologic malignancies. Preliminary results from our experience are presented for the purpose of illustrating the range of SBRT applications in gynecologic oncology.

METHODS

A comprehensive literature review was conducted and our experience from the past three years was reviewed.

RESULTS

Six case series are published that report results of SBRT for gynecologic malignancies. Sixteen gynecologic patients have been treated with SBRT at our institution. Treatment sites include pelvic and periaortic nodes (9 patients), oligometastatic disease (2), and cervical or endometrial primary tumors when other conventional external radiation or brachytherapy techniques were unsuitable (5). Preliminary follow-up at a median of 11 months (range, 0.3-33 months) demonstrates 79% locoregional control, 43% distant failure, and 50% overall survival.

CONCLUSIONS

SBRT boosts to macroscopic periaortic node recurrences and other sites seem to provide local control and a possibility of long-term disease-free survival in carefully selected patients. Previously this had been difficult to achieve with conventional radiotherapy because of the proximity of periaortic nodes to small bowel. SBRT also offers a novel approach for minimally invasive treatment in the management of gynecological cancer where current surgical and radiotherapy techniques are unsuitable.

Best of the month: A round up of articles published in recent months

With the abundant number of articles published in lung cancer, it has become very difficult to stay updated. After a search through variety of medical journal for articles published between March and June 2010, we selected the studies considered to have the greatest relevance for oncologists involved in the treatment of lung cancer. The nine selected studies covered a broad range of topics including possible hormonal role in the development of lung adenocarcinoma, lung cancer in never smokers, stereotactic radiotherapy for early-stage lung cancer, prognostic role of pleural lavage cytology, neoadjuvant chemotherapy for operable lung cancer, maintenance erlotinib, use of erlotinib after gefitinib, comparison of the two epidermal growth factor receptor tyrosine kinase inhibitors, and risk of central nervous system relapse in patients treated with epidermal growth factor receptor tyrosine kinase inhibitors.

CyberKnife radiosurgery for prostate cancer

Treatment of prostate cancer with SBRT is an area of significant controversy for many in the radiation oncology community despite radiobiologic data that strongly suggest the prostate would be an excellent SBRT target. Recently, new data have emerged that show promising outcomes with minimal toxicity for CyberKnife SBRT of prostate cancer. In the following we present the motivating factors for prostate cancer SBRT followed by a critical evaluation of the current literature and discussion of the future of prostate cancer treatment with SBRT.

Impact of Introducing Stereotactic Lung Radiotherapy for Elderly Patients With Stage I Non–Small-Cell Lung Cancer: A Population-Based Time-Trend Analysis

Purpose

Stereotactic body radiotherapy (SBRT) for stage I non–small-cell lung cancer (NSCLC) is associated with high local control rates. The impact of introducing SBRT in patients 75 years of age or older was studied using a population-based cancer registry.

Methods

The Amsterdam Cancer Registry was assessed in three eras: 1999 to 2001 (period A, pre-SBRT); 2002 to 2004 (period B, some availability of SBRT), and 2005 to 2007 (period C, full access to SBRT). χ2, Kaplan-Meier, and Cox regression were used to compare treatment patterns and overall survival (OS) in three treatment groups: surgery, radiotherapy (RT), or neither.

Results

A total of 875 elderly patients were diagnosed with stage I NSCLC in the study period. Median follow-up was 54 months. Primary treatment was surgery in 299 patients (34%), RT in 299 patients (34%), and neither in 277 patients (32%). RT use increased between periods A and C (26% v 42%, P < .01), corresponding to a decrease in untreated patients. The percentage of RT patients undergoing SBRT in periods B and C was 23% and 55%, respectively. Median survival for all patients increased from 16 months in period A to 21 months in period C (log-rank P < .01; hazard ratio [HR] = 0.65; 95% CI, 0.54 to 0.80). The improvement in OS was confined to RT patients (HR = 0.70; 95% CI, 0.49 to 0.99), whereas no significant survival improvements were seen in the other groups.

Conclusion

SBRT introduction was associated with a 16% absolute increase in RT use, a decline in the proportion of untreated elderly patients, and an improvement in OS.

Optimizing principal component models for representing interfraction variation in lung cancer radiotherapy

PURPOSE

To optimize modeling of interfractional anatomical variation during active breath-hold radiotherapy in lung cancer using principal component analysis (PCA).

METHODS

In 12 patients analyzed, weekly CT sessions consisting of three repeat intrafraction scans were acquired with active breathing control at the end of normal inspiration. The gross tumor volume (GTV) and lungs were delineated and reviewed on the first week image by physicians and propagated to all other images using deformable image registration. PCA was used to model the target and lung variability during treatment. Four PCA models were generated for each specific patient: (1) Individual models for the GTV and each lung from one image per week (week to week, W2W); (2) a W2W composite model of all structures; (3) individual models using all images (weekly plus repeat intrafraction images, allscans); and (4) composite model with all images. Models were reconstructed retrospectively (using all available images acquired) and prospectively (using only data acquired up to a time point during treatment). Dominant modes representing at least 95% of the total variability were used to reconstruct the observed anatomy. Residual reconstruction error between the model-reconstructed and observed anatomy was calculated to compare the accuracy of the models.

RESULTS

An average of 3.4 and 4.9 modes was required for the allscans models, for the GTV and composite models, respectively. The W2W model required one less mode in 40% of the patients. For the retrospective composite W2W model, the average reconstruction error was 0.7 +/- 0.2 mm, which increased to 1.1 +/- 0.5 mm when the allscans model was used. Individual and composite models did not have significantly different errors (p = 0.15, paired t-test). The average reconstruction error for the prospective models of the GTV stabilized after four measurements at 1.2 +/- 0.5 mm and for the composite model after five measurements at 0.8 +/- 0.4 mm.

CONCLUSIONS

Retrospective PCA models were capable of reconstructing original GTV and lung shapes and positions within several millimeters with three to four dominant modes, on average. Prospective models achieved similar accuracy after four to five measurements.

Clinical cancer advances 2010: annual report on progress against cancer from the American Society of Clinical Oncology

A MESSAGE FROM ASCO'S PRESIDENT

Like many health professionals who care for people with cancer, I entered the field because of specific patients who touched my heart. They still do. In an effort to weave together my personal view of what the American Society of Clinical Oncology (ASCO) stands for and the purpose the organization serves, my presidential theme this year is “Patients. Pathways. Progress.” Patients come first. Caring for patients is the most important, rewarding aspect of being an oncology professional. At its best, the relationship between doctor and patient is compassionate and honest—and a relationship of mutual respect. Many professional organizations have an interest in cancer, but no other society is so focused on the entire spectrum of cancer care, education, and research. Nor is any other society as particularly interested in bringing new treatments to our patients through clinical trials as ASCO is. Clinical trials are the crux for improving treatments for people with cancer and are critical for continued progress against the disease. “Pathways” has several meanings. Some pathways are molecular—like the cancer cell's machinery of destruction, which we have only begun to understand in recent years. But there are other equally important pathways, including the pathways new therapies follow as they move from bench to bedside and the pathways patients follow during the course of their diseases. Improved understanding of these pathways will lead to new approaches in cancer care, allowing doctors to provide targeted therapies that deliver improved, personalized treatment. The best pathway for patients to gain access to new therapies is through clinical trials. Trials conducted by the National Cancer Institute's Cooperative Group Program, a nationwide network of cancer centers and physicians, represent the United States' most important pathway for accelerating progress against cancer. This year, the Institute of Medicine released a report on major challenges facing the Cooperative Group Program. Chief among them is the fact that funding for the program has been nearly flat since 2002. ASCO has called for a doubling of funding for cooperative group research within five years and supports the full implementation of the Institute of Medicine recommendations to revitalize the program. ASCO harnesses the expertise and resources of its 28,000 members to bring all of these pathways together for the greater good of patients. Progress against cancer is being made every day—measurable both in our improved understanding of the disease and in our ability to treat it. A report issued in December 2009 by the National Cancer Institute, the Centers for Disease Control and Prevention, the American Cancer Society, and the North American Association of Central Cancer Registries found that rates of new diagnoses and rates of death resulting from all cancers combined have declined significantly in recent years for men and women overall and for most racial and ethnic populations in the United States. The pace of progress can be and needs to be hastened. Much remains to be done. Sustained national investment in cancer research is needed to bring better, more effective, less toxic treatments to people living with cancer. Pathways to progress continue in the clinic as doctors strive to find the right treatments for the right patients, to understand what represents the right treatments, and to partner with patients and caregivers for access to those treatments. This report demonstrates that significant progress is being made on the front lines of clinical cancer research. But although our nation's investment in this research is paying off, we must never forget the magnitude of what lies ahead. Cancer remains the number two killer of Americans. Future progress depends on continued commitment, from both ASCO and the larger medical community. George W. Sledge Jr, MD President American Society of Clinical Oncology

Phase I dose-escalation study of stereotactic body radiotherapy in patients with hepatic metastases

PURPOSE

To identify a tolerable and effective dose for 5-fraction stereotactic body radiotherapy for hepatic metastases.

METHODS

Patients were enrolled onto three dose-escalation cohorts: 30 Gy in 3 fractions, 50 Gy in 5 fractions, and 60 Gy in 5 fractions. Eligible patients had one to five hepatic metastases, ability to spare a critical hepatic volume (volume receiving <21 Gy) of 700 ml, adequate baseline hepatic function, no concurrent antineoplastic therapy, and a Karnofsky performance score of ≥60. Dose-limiting toxicity included treatment-related grade 3 toxicity in the gastrointestinal, hepatobiliary/pancreas, and metabolic/laboratory categories. Any grade 4 or 5 event attributable to therapy was defined as a dose-limiting toxicity. Local control (LC) and complete plus partial response rates were assessed.

RESULTS

Twenty-seven patients, 9 in each cohort, with 37 lesions were enrolled and treated: 17 men and 11 women; median age 62 (range 48-86) years; most common site of primary disease, colorectal (44.4%). Median follow-up was 20 (range 4-53) months. There was no grade 4 or 5 toxicity or treatment-related grade 3 toxicity. Actuarial 24-month LC rates for the 30-, 50-, and 60-Gy cohorts were 56%, 89%, and 100%, respectively. There was a statistically significant difference for LC between the 60- and 30-Gy cohorts (P = 0.009) but not between the 60- and 50-Gy cohorts (P = 0.56) or the 50- and 30-Gy cohorts (P = 0.091). The maximum tolerated dose was not reached.

CONCLUSIONS

A dose of 60 Gy in 5 fractions can be safely delivered to selected patients with hepatic metastases as long as the critical liver volume is respected. A dose of 60 Gy in 5 fractions yields an excellent level of LC.

A dose-volume analysis of radiation pneumonitis in non-small cell lung cancer patients treated with stereotactic body radiation therapy

PURPOSE

To examine the rates and risk factors of radiation pneumonitis (RP) in non-small cell lung cancer (NSCLC) patients treated with stereotactic body radiotherapy (SBRT).

METHODS AND MATERIALS

Dosimetry records for 251 patients with lymph node-negative Stage I-IIB NSCLC and no prior chest radiation therapy (RT) treated with SBRT were reviewed. Patients were coded on the basis of the presence of at least Grade (G) 2 RP using the Common Toxicity Criteria version 2 criteria. Radiation doses, V5, V10, V20, and mean lung dose (MLD) data points were extracted from the dose-volume histogram (DVH).

RESULTS

Median PTV volume was 48 cc. Median prescribed radiation dose was 60 Gy delivered in three fractions to the 80% isodose line. Median age at treatment was 74 years. Median follow-up was 17 months. RP was reported after treatment of 42 lesions: G1 in 19 (8%), G2 in 17 (7%), G3 in 5 (2%), and G4 in 1 (0.4%). Total lung DVHs were available for 143 patients. For evaluable patients, median MLD, V5, V10, and V20 were 4.1 Gy, 20%, 12%, and 4%, respectively. Median MLDs were 4 Gy and 5 Gy for G0-1 and G2-4 groups, respectively (p = 0.14); median V5 was 20% for G0-1 and 24% for G2-4 (p = 0.70); median V10 was 12% in G0-1 and 16% in G2-4 (p = 0.08), and median V20 was 4% in G0-1 and 6.6% in G2-4 (p = 0.05). G2-4 RP was noted in 4.3% of patients with MLD ≤4 Gy compared with 17.6% of patients with MLD >4 Gy (p = 0.02), and in 4.3% of patients with V20 ≤4% compared with 16.4% of patients with V20 >4% (p = 0.03).

CONCLUSION

Overall rate of G2-4 RP in our population treated with SBRT was 9.4%. Development of symptomatic RP in this series correlated with MLD and V20.

Annual review of advances in lung cancer clinical research: a report for the year 2009

The use of positron emission tomography compared with conventional staging increases the detection of extrathoracic metastases and reduces the number futile thoracotomies in patients being evaluated for surgical resection. Long-term follow-up of one of the two adjuvant chemotherapy trials revealed a continued overall survival (OS) benefit to adjuvant chemotherapy. In locally advanced non-small cell lung cancer, a phase III trial of chemoradiotherapy alone and with surgical resection revealed no statistically significant difference in OS between the treatment arms. In advanced stage non-small cell lung cancer, a phase III trial compared gefitinib with carboplatin and paclitaxel in a clinically enriched patient population for epidermal growth factor receptor (EGFR) tyrosine kinase (TK) mutations; among patients with an EGFR TK mutation, patients in gefitinib arm compared with carboplatin and paclitaxel arm experienced a statistically significant superior response rate and progression-free survival, and among patients without EGFR TK mutation patients in the gefitinib arm compared with carboplatin and paclitaxel experienced a statistically significant inferior response rate and progression-free survival. A phase III trial of platinum-based therapy with and without cetuximab in the first-line setting revealed improved OS in the cetuximab arm. A phase III trial of maintenance pemetrexed compared with placebo in patients who had not progressed after initial platinum-based therapy revealed an improvement in OS of patients in the pemetrexed arm with nonsquamous histology. In limited-stage small cell lung cancer, a phase III trial compared standard and high-dose prophylactic cranial irradiation and revealed no significant difference in the rate of brain metastases between the two treatment arms.

Lung density changes after stereotactic radiotherapy: a quantitative analysis in 50 patients

PURPOSE

Radiologic lung density changes are observed in more than 50% of patients after stereotactic body radiotherapy (SBRT) for lung cancer. We studied the relationship between SBRT dose and posttreatment computed tomography (CT) density changes, a surrogate for lung injury.

METHODS AND MATERIALS

The SBRT fractionation schemes used to treat Stage I lung cancer with RapidArc were three fractions of 18 Gy, five fractions of 11 Gy, or eight fractions of 7.5 Gy, prescribed at the 80% isodose. Follow-up CT scans performed at less than 6 months (n = 50) and between 6 and 9 months (n = 30) after SBRT were reviewed. Posttreatment scans were coregistered with baseline scans using a B-spline deformable registration algorithm. Voxel-Hounsfield unit histograms were created for doses between 0.5 and 50 Gy. Linear mixed effects models were used to assess the effects of SBRT dose on CT density, and the influence of possible confounders was tested.

RESULTS

Increased CT density was associated with higher dose, increasing planning target volume size, and increasing time after SBRT (all p < 0.0001). Density increases were apparent in areas receiving >6 Gy, were most prominent in areas receiving >20 Gy, and seemed to plateau above 40 Gy. In regions receiving >36 Gy, the reduction in air-filled fraction of lung after treatment was up to 18%. No increase in CT density was observed in the contralateral lung receiving ≥3 Gy.

CONCLUSIONS

A dose-response relationship exists for quantitative CT density changes after SBRT. A threshold of effect is seen at low doses, and a plateau at highest doses.

Hypoxia in models of lung cancer: implications for targeted therapeutics

PURPOSE

To efficiently translate experimental methods from bench to bedside, it is imperative that laboratory models of cancer mimic human disease as closely as possible. In this study, we sought to compare patterns of hypoxia in several standard and emerging mouse models of lung cancer to establish the appropriateness of each for evaluating the role of oxygen in lung cancer progression and therapeutic response.

EXPERIMENTAL DESIGN

Subcutaneous and orthotopic human A549 lung carcinomas growing in nude mice as well as spontaneous K-ras or Myc-induced lung tumors grown in situ or subcutaneously were studied using fluorodeoxyglucose and fluoroazomycin arabinoside positron emission tomography, and postmortem by immunohistochemical observation of the hypoxia marker pimonidazole. The response of these models to the hypoxia-activated cytotoxin PR-104 was also quantified by the formation of γH2AX foci in vitro and in vivo. Finally, our findings were compared with oxygen electrode measurements of human lung cancers.

RESULTS

Minimal fluoroazomycin arabinoside and pimonidazole accumulation was seen in tumors growing within the lungs, whereas subcutaneous tumors showed substantial trapping of both hypoxia probes. These observations correlated with the response of these tumors to PR-104, and with the reduced incidence of hypoxia in human lung cancers relative to other solid tumor types.

CONCLUSIONS

These findings suggest that in situ models of lung cancer in mice may be more reflective of the human disease, and encourage judicious selection of preclinical tumor models for the study of hypoxia imaging and antihypoxic cell therapies.

Coil spring fiducial markers placed safely using navigation bronchoscopy in inoperable patients allows accurate delivery of CyberKnife stereotactic radiosurgery

OBJECTIVES

CyberKnife stereotactic body radiosurgery is a potentially curative option for medically inoperable Stage I lung cancer. Fiducial marker placement in or near the tumor is required. Transthoracic placement using computed tomography guidance has been associated with a high risk of iatrogenic pneumothorax. Electromagnetic navigation bronchoscopy offers a safer method of placing markers; however, previous studies using linear markers have shown at least a 10% dislocation rate. We describe the use of coil-spring fiducial markers placed under moderate sedation in an outpatient bronchoscopy suite.

METHODS

A total of 52 consecutive nonoperative patients with isolated lung tumors underwent fiducial placement using electromagnetic navigation bronchoscopy. Of the 52 patients, 4 received 17 linear fiducial markers, and 49 patients with 56 tumors received 217 coil-spring fiducial markers. The procedures were considered successful if the fiducial markers had been placed in or near the tumors and had remained in place without migration, allowing radiosurgery without the need for additional fiducial markers.

RESULTS

A total of 234 fiducial markers were successfully deployed in 52 patients with 60 tumors (mean diameter 23.7 mm). Of these 60 tumors, 35 (58%) were adjacent to the pleura. At CyberKnife planning, 8 (47%) of 17 linear fiducial markers and 215 (99%) of 217 coil-spring fiducial markers (P = .0001) were still in place. Of the 4 patients with linear fiducial markers, 2 required additional fiducial placements; none of the patients with coil fiducial markers required additional procedures. Three pneumothoraces (5.8%) occurred in peripheral lesions (2 were treated with a pig-tail chest tube and 1 with observation only).

CONCLUSIONS

Deployment of coil spring fiducial markers using navigation bronchoscopy can safely be performed with the patient under moderate sedation with almost no migration and a 5.8% rate of pneumothorax.

Clinical outcomes of stereotactic body radiotherapy for stage I non-small cell lung cancer using different doses depending on tumor size

BACKGROUND

The treatment schedules for stereotactic body radiotherapy (SBRT) for lung cancer vary from institution to institution. Several reports have indicated that stage IB patients had worse outcomes than stage IA patients when the same dose was used. We evaluated the clinical outcomes of SBRT for stage I non-small cell lung cancer (NSCLC) treated with different doses depending on tumor diameter.

METHODS

Between February 2004 and November 2008, 124 patients with stage I NSCLC underwent SBRT. Total doses of 44, 48, and 52 Gy were administered for tumors with a longest diameter of less than 1.5 cm, 1.5-3 cm, and larger than 3 cm, respectively. All doses were given in 4 fractions.

RESULTS

For all 124 patients, overall survival was 71%, cause-specific survival was 87%, progression-free survival was 60%, and local control was 80%, at 3 years. The 3-year overall survival was 79% for 85 stage IA patients treated with 48 Gy and 56% for 37 stage IB patients treated with 52 Gy (p = 0.05). At 3 years, cause-specific survival was 91% for the former group and 79% for the latter (p = 0.18), and progression-free survival was 62% versus 54% (p = 0.30). The 3-year local control rate was 81% versus 74% (p = 0.35). The cumulative incidence of grade 2 or 3 radiation pneumonitis was 11% in stage IA patients and 30% in stage IB patients (p = 0.02).

CONCLUSIONS

There was no difference in local control between stage IA and IB tumors despite the difference in tumor size. The benefit of increasing the SBRT dose for larger tumors should be investigated further.

The role of stereotactic body radiotherapy in the management of non-small cell lung cancer: an emerging standard for the medically inoperable patient?

The standard of care for early-stage lung cancer is surgical resection. Many patients with this diagnosis have comorbidities that preclude oncologic resection. Randomized data show that limited resection is inadequate for local disease control and may negatively impact on survival. Stereotactic body radiotherapy (SBRT) has emerged as a novel radiation modality with significant applications in the inoperable, early-stage lung cancer population. Retrospective and prospective studies published in the past decade have established the feasibility, safety, and efficacy of SBRT in these patients using a variety of dose regimens and technologies. To date, lung SBRT results demonstrate excellent local control with very little acute toxicity, and suggest improved overall survival compared to historical controls of fractionated radiotherapy. Ongoing prospective trials are exploring dose and fractionation schedules in the inoperable population, and are starting to explore the role of SBRT for the operable patient.

Stereotactic Body Radiation Therapy (SBRT) for Unresectable Pancreatic Carcinoma

Survival in patients with unresectable pancreatic carcinoma is poor. Studies by Mayo Clinic and the Gastrointestinal Tumor Study Group (GITSG) have established combined modality treatment with chemotherapy and radiation as the standard of care. Use of gemcitabine-based chemotherapy alone has also been shown to provide a benefit, but 5‑year overall survival still remains less than 5%. Conventional radiotherapy is traditionally delivered over a six week period and high toxicity is seen with the concomitant use of chemotherapy. In contrast, SBRT can be delivered in 3–5 days and, when used as a component of combined modality therapy with gemcitabine, disruption to the timely delivery of chemotherapy is minimal. Early single-institution reports of SBRT for unresectable pancreatic carcinoma demonstrate excellent local control with acceptable toxicity. Use of SBRT in unresectable pancreatic carcinoma warrants further investigation in order to improve the survival of patients with historically poor outcomes.

21 years of biologically effective dose

In 1989 the British Journal of Radiology published a review proposing the term biologically effective dose (BED), based on linear quadratic cell survival in radiobiology. It aimed to indicate quantitatively the biological effect of any radiotherapy treatment, taking account of changes in dose-per-fraction or dose rate, total dose and (the new factor) overall time. How has it done so far? Acceptable clinical results have been generally reported using BED, and it is in increasing use, although sometimes mistaken for "biologically equivalent dose", from which it differs by large factors, as explained here. The continuously bending nature of the linear quadratic curve has been questioned but BED has worked well for comparing treatments in many modalities, including some with large fractions. Two important improvements occurred in the BED formula. First, in 1999, high linear energy transfer (LET) radiation was included; second, in 2003, when time parameters for acute mucosal tolerance were proposed, optimum overall times could then be "triangulated" to optimise tumour BED and cell kill. This occurs only when both early and late BEDs meet their full constraints simultaneously. New methods of dose delivery (intensity modulated radiation therapy, stereotactic body radiation therapy, protons, tomotherapy, rapid arc and cyberknife) use a few large fractions and obviously oppose well-known fractionation schedules. Careful biological modelling is required to balance the differing trends of fraction size and local dose gradient, as explained in the discussion "How Fractionation Really Works". BED is now used for dose escalation studies, radiochemotherapy, brachytherapy, high-LET particle beams, radionuclide-targeted therapy, and for quantifying any treatments using ionising radiation.