Stereotactic ablative radiotherapy for operable stage I non-small-cell lung cancer (revised STARS): long-term results of a single-arm, prospective trial with prespecified comparison to surgery.

BACKGROUND: A previous pooled analysis of the STARS and ROSEL trials showed higher survival after stereotactic ablative radiotherapy (SABR) than with surgery for operable early-stage non-small-cell lung cancer (NSCLC), but that analysis had notable limitations. This study reports long-term results of the revised STARS trial, in which the SABR group was re-accrued with a larger sample size, along with a protocol-specified propensity-matched comparison with a prospectively registered, contemporary institutional cohort of patients who underwent video-assisted thoracoscopic surgical lobectomy with mediastinal lymph node dissection (VATS L-MLND). METHODS: This single-arm prospective trial was done at the University of Texas MD Anderson Cancer Center (Houston, TX, USA) and enrolled patients aged 18 years or older with a Zubrod performance status of 0-2, newly diagnosed and histologically confirmed NSCLC with N0M0 disease (squamous cell, adenocarcinoma, large cell, or NSCLC not otherwise specified), and a tumour diameter of 3 cm or less. This trial did not include patients from the previous pooled analysis. SABR dosing was 54 Gy in three fractions (for peripheral lesions) or 50 Gy in four fractions (for central tumours; simultaneous integrated boost to gross tumour totalling 60 Gy). The primary endpoint was the 3-year overall survival. For the propensity-matching analysis, we used a surgical cohort from the MD Anderson Department of Thoracic and Cardiovascular Surgery's prospectively registered, institutional review board-approved database of all patients with clinical stage I NSCLC who underwent VATS L-MLND during the period of enrolment in this trial. Non-inferiority could be claimed if the 3-year overall survival rate after SABR was lower than that after VATS L-MLND by 12% or less and the upper bound of the 95% CI of the hazard ratio (HR) was less than 1·965. Propensity matching consisted of determining a propensity score using a multivariable logistic regression model including several covariates (age, tumour size, histology, performance status, and the interaction of age and sex); based on the propensity scores, one patient in the SABR group was randomly matched with one patient in the VATS L-MLND group using a 5:1 digit greedy match algorithm. This study is registered with ClinicalTrials.gov, NCT02357992. FINDINGS: Between Sept 1, 2015, and Jan 31, 2017, 80 patients were enrolled and included in efficacy and safety analyses. Median follow-up time was 5·1 years (IQR 3·9-5·8). Overall survival was 91% (95% CI 85-98) at 3 years and 87% (79-95) at 5 years. SABR was tolerated well, with no grade 4-5 toxicity and one (1%) case each of grade 3 dyspnoea, grade 2 pneumonitis, and grade 2 lung fibrosis. No serious adverse events were recorded. Overall survival in the propensity-matched VATS L-MLND cohort was 91% (95% CI 85-98) at 3 years and 84% (76-93) at 5 years. Non-inferiority was claimed since the 3-year overall survival after SABR was not lower than that observed in the VATS L-MLND group. There was no significant difference in overall survival between the two patient cohorts (hazard ratio 0·86 [95% CI 0·45-1·65], p=0·65) from a multivariable analysis. INTERPRETATION: Long-term survival after SABR is non-inferior to VATS L-MLND for operable stage IA NSCLC. SABR remains promising for such cases but multidisciplinary management is strongly recommended. FUNDING: Varian Medical Systems and US National Cancer Institute (National Institutes of Health).

Mitigating the impact of COVID-19 on oncology: Clinical and operational lessons from a prospective radiation oncology cohort tested for COVID-19.

BACKGROUND AND PURPOSE: The COVID-19 pandemic warrants operational initiatives to minimize transmission, particularly among cancer patients who are thought to be at high-risk. Within our department, a multidisciplinary tracer team prospectively monitored all patients under investigation, tracking their test status, treatment delays, clinical outcomes, employee exposures, and quarantines. MATERIALS AND METHODS: Prospective cohort tested for SARS-COV-2 infection over 35 consecutive days of the early pandemic (03/19/2020-04/22/2020). RESULTS: A total of 121 Radiation Oncology patients underwent RT-PCR testing during this timeframe. Of the 7 (6%) confirmed-positive cases, 6 patients were admitted (4 warranting intensive care), and 2 died from acute respiratory distress syndrome. Radiotherapy was deferred or interrupted for 40 patients awaiting testing. As the median turnaround time for RT-PCR testing decreased from 1.5 (IQR: 1-4) to ≤1-day (P < 0.001), the median treatment delay also decreased from 3.5 (IQR: 1.75-5) to 1 business day (IQR: 1-2) [P < 0.001]. Each patient was an exposure risk to a median of 5 employees (IQR: 3-6.5) through prolonged close contact. During this timeframe, 39 care-team members were quarantined for a median of 3 days (IQR: 2-11), with a peak of 17 employees simultaneously quarantined. Following implementation of a "dual PPE policy," newly quarantined employees decreased from 2.9 to 0.5 per day. CONCLUSION: The severe adverse events noted among these confirmed-positive cases support the notion that cancer patients are vulnerable to COVID-19. Active tracking, rapid diagnosis, and aggressive source control can mitigate the adverse effects on treatment delays, workforce incapacitation, and ideally outcomes.

Thoracic Radiation Oncology Clinical Trial Accrual and Reasons for Nonenrollment: Results of a Large, Prospective, Multiyear Analysis.

PURPOSE: Clinical trials are considered the gold standard in evidence-based medicine, yet few patients with cancer ultimately enroll. Here we examine patients screened for thoracic radiation oncology clinical trials to better understand enrollment trends. METHODS AND MATERIALS: A prospective database tracking screening and enrollment for patients referred for thoracic radiation oncology consultation at our institution from 2016 to 2019 was evaluated. Proportional enrollment rates, patient and disease characteristics, self-reported socioeconomic factors, and reasons for ineligibility or nonenrollment across 17 radiation therapy trials were compared. RESULTS: Enrollment data on 2372 patients were available for analysis. Of these patients, 40.0% (949) were deemed "not eligible" (NE) for any trial or were unwilling to be further screened. Reasons for ineligibility included stage (44%), histology (13%), radiation therapy not indicated (12%), patient decision (7%), and enrollment in a competing medical or surgical oncology trial (5%). The remaining 60.0% (1423) were "potentially eligible" (PE) for one or more trials. Most had non-small cell lung cancer (71%) or esophageal cancer (16%), and there were significantly fewer stage IV PE (29%) versus NE (49%) patients (P < .0001). Of 2372 patients, 281 (11.9%) enrolled. Notable reasons for nonenrollment were inclusion and exclusion criteria (58%), patients declining enrollment (14%), and physician decision (5%). The proportion of white patients was higher in the PE versus NE group (82.5% vs 75.8%; P < .001). Additionally, white race (87.9% vs 81.2%; P = .008), English language preference (96.4% vs 92.9%; P = .032), and non-Hispanic/Latino ethnicity (94.0% vs 90.1%; P = .042) were significantly different in enrolled versus nonenrolled PE patients. CONCLUSIONS: Only 12% of patients screened for radiation therapy trials ultimately enrolled, and more than two-thirds had no trial available or were found ineligible. In addition, 19% of potential eligible patients did not enroll because the patient or physician declined. Future trials may benefit from pragmatic designs with more inclusive enrollment criteria and multidisciplinary engagement of referring providers.

Randomized Phase IIB Trial of Proton Beam Therapy Versus Intensity-Modulated Radiation Therapy for Locally Advanced Esophageal Cancer.

PURPOSE: Whether dosimetric advantages of proton beam therapy (PBT) translate to improved clinical outcomes compared with intensity-modulated radiation therapy (IMRT) remains unclear. This randomized trial compared total toxicity burden (TTB) and progression-free survival (PFS) between these modalities for esophageal cancer. METHODS: This phase IIB trial randomly assigned patients to PBT or IMRT (50.4 Gy), stratified for histology, resectability, induction chemotherapy, and stage. The prespecified coprimary end points were TTB and PFS. TTB, a composite score of 11 distinct adverse events (AEs), including common toxicities as well as postoperative complications (POCs) in operated patients, quantified the extent of AE severity experienced over the duration of 1 year following treatment. The trial was conducted using Bayesian group sequential design with three planned interim analyses at 33%, 50%, and 67% of expected accrual (adjusted for follow-up). RESULTS: This trial (commenced April 2012) was approved for closure and analysis upon activation of NRG-GI006 in March 2019, which occurred immediately prior to the planned 67% interim analysis. Altogether, 145 patients were randomly assigned (72 IMRT, 73 PBT), and 107 patients (61 IMRT, 46 PBT) were evaluable. Median follow-up was 44.1 months. Fifty-one patients (30 IMRT, 21 PBT) underwent esophagectomy; 80% of PBT was passive scattering. The posterior mean TTB was 2.3 times higher for IMRT (39.9; 95% highest posterior density interval, 26.2-54.9) than PBT (17.4; 10.5-25.0). The mean POC score was 7.6 times higher for IMRT (19.1; 7.3-32.3) versus PBT (2.5; 0.3-5.2). The posterior probability that mean TTB was lower for PBT compared with IMRT was 0.9989, which exceeded the trial's stopping boundary of 0.9942 at the 67% interim analysis. The 3-year PFS rate (50.8% v 51.2%) and 3-year overall survival rates (44.5% v 44.5%) were similar. CONCLUSION: For locally advanced esophageal cancer, PBT reduced the risk and severity of AEs compared with IMRT while maintaining similar PFS.

Metabolic Responses to Metformin in Inoperable Early-stage Non-Small Cell Lung Cancer Treated With Stereotactic Radiotherapy: Results of a Randomized Phase II Clinical Trial.

BACKGROUND: Metformin reduces glucose uptake in physiologic tissues and has been shown to affect non-small cell lung cancer (NSCLC) metabolism. We hypothesized that positron emission tomography (PET) scans could detect the impact of metformin on glucose uptake in NSCLC and we sought to test this hypothesis in a prospective clinical trial. MATERIALS AND METHODS: A single-blinded phase II clinical trial was performed with subjects randomized 6:1 to 3 to 4 weeks of metformin versus placebo for inoperable early-stage NSCLC. PET scans were performed at baseline, mid-treatment (after 2 wk study medication), and 6 months postradiation. The primary endpoint of the trial was tumor metabolic response to metformin by PERCIST before definitive radiation. Stereotactic body radiotherapy to 50 Gy in 4 fractions was used for peripheral tumors and 70 Gy in 10 fractions for central tumors. RESULTS: There were 14 subjects randomized to the metformin and 1 to placebo. Histologies were 60% adenocarcinoma, 33.3% squamous cell carcinoma, and 6.7% poorly differentiated carcinoma. At mid-treatment PET scan, 57% of subjects randomized to metformin met PERCIST criteria for metabolic response, of which 75% had progressive metabolic disease and 25% had partial metabolic response, whereas the placebo subject had stable metabolic disease. At 6 months, the metformin arm had 69% complete metabolic response, 23% partial metabolic response and 1 progressive metabolic disease, and the subject treated with placebo had a complete metabolic response. There were no CTCAE grade ≥3 toxicities. CONCLUSIONS: Despite low accrual, majority of subjects treated with metformin had metabolic responses by PERCIST criteria on PET imaging. Contrary to the effect of metformin on most physiologic tissues, most tumors had increased metabolic activity in response to metformin.

Phase II Trial of Concurrent Atezolizumab With Chemoradiation for Unresectable NSCLC.

INTRODUCTION: Consolidation durvalumab after chemoradiation (CRT) is the current standard of care for locally advanced NSCLC. We hypothesized that adding immunotherapy concurrently with CRT (cCRT) would increase efficacy without additive toxicity. METHODS: This phase II study was conducted in two parts. Part 1 (n = 10) involved administration of conventionally fractionated CRT followed by consolidation chemotherapy (atezolizumab [two cycles] and maintenance atezolizumab up to 1 y). Part 2 (n = 30) involved administration of cCRT with atezolizumab followed by the same consolidation and maintenance therapies as in part 1. Programmed cell death ligand-1 staining cutoffs (1% or 50%) using Dako 22C3 immunohistochemistry were correlated with clinical outcomes. RESULTS: The overall toxicities for part 1/2 were overall adverse events of grade 3 and above of 80%/80%; immune-related adverse events of grade 3 and above of 30%/20%; and pneumonitis of grade 2 and above of 10%/16%, respectively. In part 1, for preliminary efficacy results, with a median follow-up of 22.5 months, the median progression-free survival was 18.6 months, and the overall survival was 22.8 months. In part 2, with a median follow-up time of 15.1 months, the median progression-free survival was 13.2 months, and the overall survival was not reached. There was no difference in cancer recurrence regardless of programmed cell death ligand-1 status. CONCLUSIONS: Atezolizumab with cCRT is safe and feasible and has no added toxicities compared with historical rates.

Simultaneous Integrated Boost for Radiation Dose Escalation to the Gross Tumor Volume With Intensity Modulated (Photon) Radiation Therapy or Intensity Modulated Proton Therapy and Concurrent Chemotherapy for Stage II to III Non-Small Cell Lung Cancer: A Phase 1 Study.

PURPOSE: To establish, in the phase 1 portion of a prospective phase 1/2 study, the maximum tolerated dose of image guided intensity modulated radiation therapy (IMRT) or proton therapy (IMPT), both with a simultaneous integrated boost (SIB), for patients with stage II to IIIB non-small cell lung cancer receiving concurrent chemoradiation therapy. METHODS AND MATERIALS: Patients had pathologically proven non-small cell lung cancer, either unresectable stage II to IIIB disease or recurrent disease after surgical resection, and could tolerate concurrent chemoradiation. Radiation doses were selectively escalated to the SIB volume (internal gross tumor volume + 5-mm margin), and the dose to the planning target volume (internal gross tumor volume + 8-mm margin for clinical target volume + 5 mm) was kept at 60 Gy [cobalt gray equivalent (CGE)] over 30 fractions. Patients were randomized between the IMRT and IMPT groups if slots were available on the treatment machines for both groups. Otherwise, patients were allocated to IMRT or IMPT, whichever had an open treatment slot on the machine without randomization. RESULTS: Fifteen patients (6 IMRT, 9 IMPT) were enrolled. The highest doses to the SIB were 72 Gy in the IMRT group and 78 Gy(CGE) in the IMPT group. Nine patients (6 IMRT, 3 IMPT) received an SIB dose of 72 Gy(CGE) [biologically effective dose = 89.3 Gy(CGE)], and 6 patients (IMPT) received an SIB dose of 78 Gy(CGE) [biologically effective dose = 98.3 Gy(CGE)]. Dose-limiting (grade ≥3) toxicity (esophagitis) developed in 1 of the 9 patients given 72 Gy(CGE) SIB. Grade ≥3 pneumonitis developed in 2 of the 6 patients treated to 78 Gy(CGE) IMPT SIB: 1 (grade 3) at 3 months after treatment and the other (grade 5, possibly related to treatment) at 2 months after treatment. Only 1 patient developed a marginal tumor recurrence with a median follow-up of 25 months (range, 4.3-47.4 months). CONCLUSIONS: We recommend that an SIB dose of 72 Gy(CGE) be used as the highest SIB dose for the planned randomized phase 2 study.

Incidence of Second Malignancy after Successful Treatment of Limited-Stage Small-Cell Lung Cancer and Its Effects on Survival.

INTRODUCTION: Extended survival outcomes from improved treatments for patients with cancer come with an increased risk for development of a metachronous second malignancy (MSM). We evaluated the incidence of MSM after successful treatment of SCLC and compared survival between patients with SCLC in whom MSM developed and those in whom it did not. METHODS: Selection criteria were a diagnosis of limited-stage SCLC and receipt of at least 45 Gy of radiotherapy and chemotherapy at a single institution in 1985-2012. MSM was defined as a tumor of a different histologic type than the primary that appeared more than 2 years after the diagnosis of SCLC. RESULTS: Of 704 patients identified, 32 were excluded for lack of follow-up, 48 for having SCLC as MSM after treatment of another type of cancer, 37 for nonmelanoma skin cancer as MSM, and 46 for MSM within 2 years after SCLC diagnosis. Of the remaining 541 patients, 346 had recurrent SCLC, 180 had no second malignancy and no recurrence, and 15 (2.8%) had MSM (13 in a lung [eight adenocarcinomas and five squamous cell carcinomas], one sarcoma, and one acute myeloid leukemia). All 15 patients with MSM achieved complete response to the SCLC treatment. Overall survival was longer for patients with MSM than for patients with no other malignancies and no recurrence, with 10-year rates of 61.9% (95% confidence interval: 30.0%-82.6%) and 29.9% (95% confidence interval: 21.5%-38.6%), respectively (p = 0.03). CONCLUSIONS: Long-term survivors after treatment for SCLC should be made aware of the risk for MSM and the necessity of follow-up.

7-year follow-up after stereotactic ablative radiotherapy for patients with stage I non-small cell lung cancer: Results of a phase 2 clinical trial.

BACKGROUND: The authors evaluated the efficacy, patterns of failure, and toxicity of stereotactic ablative radiotherapy (SABR) for patients with medically inoperable, clinical stage I non-small cell lung cancer (NSCLC) in a prospective clinical trial with 7 years of follow-up. Clinical staging was performed according to the seventh edition of the American Joint Committee on Cancer TNM staging system. METHODS: Eligible patients with histologically confirmed NSCLC of clinical stage I as determined using positron emission tomography staging were treated with SABR (50 grays in 4 fractions). The primary endpoint was progression-free survival. Patients were followed with computed tomography and/or positron emission tomography/computed tomography every 3 months for the first 2 years, every 6 months for the next 3 years, and then annually thereafter. RESULTS: A total of 65 patients were eligible for analysis. The median age of the patients was 71 years, and the median follow-up was 7.2 years. A total of 18 patients (27.7%) developed disease recurrence at a median of 14.5 months (range, 4.3-71.5 months) after SABR. Estimated incidences of local, regional, and distant disease recurrence using competing risk analysis were 8.1%, 10.9%, and 11.0%, respectively, at 5 years and 8.1%, 13.6%, and 13.8%, respectively, at 7 years. A second primary lung carcinoma developed in 12 patients (18.5%) at a median of 35 months (range, 5-67 months) after SABR. Estimated 5-year and 7-year progression-free survival rates were 49.5% and 38.2%, respectively; the corresponding overall survival rates were 55.7% and 47.5%, respectively. Three patients (4.6%) experienced grade 3 treatment-related adverse events. No patients developed grade 4 or 5 adverse events (toxicity was graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events [version 3.0]). CONCLUSIONS: With long-term follow-up, the results of the current prospective study demonstrated outstanding local control and low toxicity after SABR in patients with clinical stage I NSCLC. Regional disease recurrence and distant metastases were the dominant manifestations of failure. Surveillance for second primary lung carcinoma is recommended. Cancer 2017;123:3031-39. © 2017 American Cancer Society.

Is sex associated with the outcome of patients treated with radiation for nonsmall cell lung cancer?

BACKGROUND: Lung cancer is the leading cause of cancer death for both men and women, but the disease course differs between the sexes. To the authors' knowledge, sex-based differences in outcomes among the population of nonsmall cell lung cancer (NSCLC) patients receiving radiation have not been well defined. METHODS: Data for 831 patients (319 women and 512 men) with stage I to III NSCLC and treated with > or =45 Gray of radiation between March 1985 and November 2003 were retrospectively analyzed (grading determined according to the 1997 American Joint Committee on Cancer grading system). RESULTS: Women were more likely to have earlier stage disease, to have smoked <50 pack-years, and to have adenocarcinoma or large-cell carcinoma (all P < or = .001). For each stage, treatment did not differ between women and men. Five-year survival rates were significantly better for women than for men: overall survival (OS), 28.6% versus 16.1% (P < .001); disease-free survival, 31.2% versus 20.1% (P = .02); and distant metastasis-free survival, 48.8% versus 37.6% (P < .02). Among patients with medically inoperable stage I NSCLC, women had improved 5-year OS compared with men (30.0% vs 13.1%; P = .004). On multivariate analysis, male sex, weight loss, age > or =65 years, and stage III disease were found to be associated with poorer OS (all P < 0.02). CONCLUSIONS: Although women are more likely to have earlier stage disease, among patients with medically inoperable stage I NSCLC, women still have a better OS. Along with known prognostic factors, including age, weight loss, and stage, sex remained significant on multivariate analysis of OS, suggesting that sex is a determinant of outcome in NSCLC patients receiving radiation.

Potential dosimetric benefits of four-dimensional radiation treatment planning.

PURPOSE: To determine the extent of dosimetric differences between conventional three-dimensional (3D) dose calculations and four-dimensional (4D) dose calculations based on deformation of organ models. METHODS AND MATERIALS: Four-dimensional dose calculations were retrospectively performed on computed tomography data sets for 15 patients with Stage III non-small-cell lung cancer, using a model-based deformable registration algorithm on a research version of a commercial radiation treatment planning system. Target volume coverage and doses to critical structures calculated using the 4D methodology were compared with those calculated using conventional 3D methodology. RESULTS: For 11 of 15 patients, clinical target volume coverage was comparable in the 3D and 4D calculations, whereas for 7 of 15 patients, planning target volume coverage was comparable. For the other patients, the 4D calculation indicated a difference in target volume dose sufficiently great to warrant replanning. No correlations could be established between differences in 3D and 4D calculations and gross tumor volume size or extent of motion. Negligible differences were observed between 3D and 4D dose-volume relationships for normal anatomic structures. CONCLUSIONS: Use of 4D dose calculations, when possible, helps ensure that target volumes will not be underirradiated when respiratory motion may affect the dose distribution.

Dose-dependent pulmonary toxicity after postoperative intensity-modulated radiotherapy for malignant pleural mesothelioma.

PURPOSE: To determine the incidence of fatal pulmonary events after extrapleural pneumonectomy and hemithoracic intensity-modulated radiotherapy (IMRT) for malignant pleural mesothelioma. METHODS AND MATERIALS: We retrospectively reviewed the records of 63 consecutive patients with malignant pleural mesothelioma who underwent extrapleural pneumonectomy and IMRT at the University of Texas M. D. Anderson Cancer Center. The endpoints studied were pulmonary-related death (PRD) and non-cancer-related death within 6 months of IMRT. RESULTS: Of the 63 patients, 23 (37%) had died within 6 months of IMRT (10 of recurrent cancer, 6 of pulmonary causes [pneumonia in 4 and pneumonitis in 2], and 7 of other noncancer causes [pulmonary embolus in 2, sepsis after bronchopleural fistula in 1, and cause unknown but without pulmonary symptoms or recurrent disease in 4]). On univariate analysis, the factors that predicted for PRD were a lower preoperative ejection fraction (p = 0.021), absolute volume of lung spared at 10 Gy (p = 0.025), percentage of lung volume receiving >or=20 Gy (V(20); p = 0.002), and mean lung dose (p = 0.013). On multivariate analysis, only V20 was predictive of PRD (p = 0.017; odds ratio, 1.50; 95% confidence interval, 1.08-2.08) or non-cancer-related death (p = 0.033; odds ratio, 1.21; 95% confidence interval, 1.02-1.45). CONCLUSION: The results of our study have shown that fatal pulmonary toxicities were associated with radiation to the contralateral lung. V20 was the only independent determinant for risk of PRD or non-cancer-related death. The mean V20 of the non-PRD patients was considerably lower than that accepted during standard thoracic radiotherapy, implying that the V20 should be kept as low as possible after extrapleural pneumonectomy.

Gemcitabine-induced radiation recall.

PURPOSE: To study and report 6 patients with radiation recall in unique sites, secondary to gemcitabine chemotherapy. METHODS AND MATERIALS: The clinical presentations and outcomes of 6 patients with radiation recall secondary to gemcitabine chemotherapy were retrospectively analyzed over the course of a 1-year period. RESULTS: Radiation recall reactions were seen in the central nervous system, skin, gastrointestinal tract, and in the lymphatic and musculoskeletal systems. The time between initiation of radiation and recall of the radiation phenomenon ranged from 3 weeks to 8 months from the time gemcitabine was initiated. The usual dosage of gemcitabine in these cases was 1000 mg/m(2) given on a weekly basis. No radiation therapy was given concomitantly with gemcitabine. Treatment of the recall reaction consisted of discontinuing gemcitabine and initiating steroid therapy, supportive therapy, and/or nonsteroidal anti-inflammatory agents. Minimal improvement was seen in 3 out of 6 patients, and resolution of the radiation recall was seen in 3 out of 6 patients. A comprehensive review of the literature revealed that radiation recall with gemcitabine has been related to skin reactions only; no previous cases of radiation recall occurring in the central nervous system have been reported with any chemotherapy agent. CONCLUSION: Radiation recall from gemcitabine chemotherapy is rare, but can potentially arise in any site that has been previously irradiated. Treating physicians must be aware of this potential toxicity from gemcitabine and radiation and discontinue the gemcitabine if radiation recall is observed.