The Interplay Effect and Mitigations with Cyclotron and Linac Proton Beam Scanning for Lung SBRT

PURPOSE/OBJECTIVE(S)

To evaluate the impact of different types of pencil beam scanning proton accelerators and spot sizes on interplay effects, mitigations, and plan quality for lung cancer patients treated with SBRT.

MATERIALS/METHODS

Twenty lung cancer patients (ten peripheral and ten central tumors) treated in our institution with photon SBRT were selected to represent varying tumor volumes and respiratory motion amplitudes for this retrospective study. The respiratory motion amplitude ranged from 0.1 to 1.0 cm with compression. For each patient, plans were created using: 1) cyclotron-generated proton beams (CPB) (σ: 2.7-7.0 mm); 2) linear accelerator proton beams (LPB) (σ: 2.9-5.5 mm); and 3) linear accelerator proton minibeams (LPMB) (σ: 0.9-3.9 mm). Plans were robustly optimized on the GTV using each individual 4DCT phase. Single-filed optimization (SFO) plans were the first attempt, and if the plan quality did not meet the dosimetric requirement, multi-field optimization (MFO) was used. MFO plans were created for all patients for comparison. For each patient, all plans were normalized to have the same dose to 99% of the GTV. Interplay effects were evaluated for ten scenarios of treatment delivery starting in ten breathing phases using machine generic time models and a constant breathing period of 4 seconds. Volumetric repainting (VR) was performed 2-6 times for each plan. To assess plan quality in the nominal scenario, we compared the conformity index (CI), R50, and the percentage of lung volume receiving 20 Gy (RBE) (V20Gy). CI is defined as the ratio of the 100% isodose volume to the GTV. R50 is defined as the 50% isodose volume divided by the GTV. Dmax and V18Gy of the proximal bronchial tree (PBT) were evaluated for central tumors.

RESULTS

Twelve of 20 plans can be optimized sufficiently with SFO. In interplay effect evaluation, the mean V100%RX values of the GTV were 99.42±0.6%, 97.52±3.9%, and 94.49±7.3%for CPB, LPB, and LPMB plans respectively. After VR 2/3/5 times, the V100%RX values were improved (on average) by 0.13%/1.84%/4.63% for CPB/LPB/LPMB plans. The delivery time for VR plans was the lowest for LPB plans, while delivery time for LPMB was on average 1 minute longer than CPB plans. VR showed no effect on lung V20Gy, Dmax and V18Gy of the PBT. SFO plans were more robust against the interplay effect compared with MFO plans for LPB and LPMB. Average CIs of 1.88±0.4, 1.79±0.4, and 1.75±0.4; average R50s of 7.99±4.0, 6.68±3.0, and 5.70±2.6; and average lung V20Gy values of 2.81±1.5, 2.26±1.3, and 1.85±1.1 were obtained for CPB, LPB, and LPMB plans, respectively. Dmax and V18Gy of the PBT decreased with decreasing spot sizes.

CONCLUSION

LPMB, with the smallest spot size, produced superior plan quality. In the absence of VR, proton machines with large spot sizes generated more robust plans against interplay effects. VR improved the plan robustness against interplay effects for modalities with small spot sizes and fast energy changes, preserving the low dose sparing aspect of the LPMB, even when motion is included.

Change in Quality of Life after Stereotactic Body Radiation Therapy (SBRT) on a Prospective Trial of Peripheral Stage I or II Non-Small Cell Lung Cancer Predicts Survival

PURPOSE/OBJECTIVE(S)

We previously reported the results of a randomized, multi-institutional phase II clinical trial evaluating one versus three fractions of SBRT for peripheral Stage I to II non-small cell lung cancer (NSCLC). A secondary objective to compare quality of life (QOL) data and its association with survival outcomes is reported.

MATERIALS/METHODS

Medically inoperable patients with biopsy-proven peripheral T1-2N0M0 NSCLC were enrolled. Patients were randomized to 30 Gy in 1 fraction (arm 1) or 60 Gy in 3 fractions (arm 2) and stratified by performance status. QOL scores from the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30) and EORTC QLQ Lung Cancer-Specific Module (EORTC QLQ-LC13) questionnaires were required at baseline and each follow-up visit. Univariate models were generated to evaluate associations between QOL scores and survival with 95% confidence intervals (CI) calculated at each time point.

RESULTS

Among 98 patients enrolled (49 in each arm), 88 patients had data available for QOL analysis. At 6 month follow up, patients with stable or decreased (n = 49) versus those with increased global QOL scores (n = 27) had worse progression-free survival (HR [Hazards' Ratio] 2.32 [CI, 1.14-4.73], p = 0.021) and overall survival (HR 2.13 [CI, 1.01-4.51], p = 0.048). Similar results persisted at the 12 month follow up for progression-free survival (HR 3.90 [CI, 1.52-10.04], p = 0.016) and overall survival (HR 3.25 [CI, 1.25-8.43], p = 0.016). Median overall survival for patients with stable or decreased global QOL versus increased global QOL at 6 month follow up was 39.0 vs 60.3 months (p = 0.032).

CONCLUSION

Change in QOL is an early predictor of survival following SBRT for patients with peripheral early-stage NSCLC.

Single-Fraction Lung SBRT Outcomes for Tumors ≥ 3cm

PURPOSE/OBJECTIVE(S)

Toxicity and local control at 1 year were the primary and secondary endpoints, respectively, of two randomized phase II lung SBRT trials having a single fraction (SF-SBRT) arm. Median tumor size in these trials was 2 cm. We surveyed our institutional database to analyze outcomes for tumors 3 cm or greater.

MATERIALS/METHODS

A survey from 2003-2022 of 2481 patients (pts) in an IRB-approved prospective registry yielded 61 pts [2.5%] treated with SF-SBRT for tumors > 3cm. SF-SBRT dose was either 34 Gy or 30 Gy in one fraction. Outcomes of interest included rates of local control (LC) as well as treatment-related toxicity graded per CTCAE version 4.0. Gray's test and Log rank test were used to assess significance for disease recurrence and overall survival (OS), respectively.

RESULTS

For the 61 pts, median follow up interval was 12.2 months (m). Pt characteristics included: female (57.4%); median age 76.8 years (range 56.5-94.3); median KPS 80 (range 50-100); active smokers 11.5%; median body mass-index 25.8 (range 16.4-48.8). Tumor characteristics included: median diameter 3.3 cm (range 3.0-6.6) with tumor size cohorts (% of total) being: 3-3.9 cm (73.8%); 4-4.9 cm (21.3%); 5-6.6 cm (4.9%); median PET SUVmax 9.1 (range 1.7-41.5); 6.6% were oligometastatic and 3.3% oligoprogressive; 93.4% were biopsy-proven with adenocarcinoma being 45.9%; 49.2% abutted the chest wall. SF-SBRT dose was 34 Gy in 80.3% cases and 30 Gy in 19.7%. At analysis, toxicity of any grade/type was seen in 27.5% pts, with no > grade 3 cases; 6.6% of pts had grade 2 chest wall toxicity. Rates (in %) of local, lobar, nodal and distant failure were 1.7, 1.7, 13.1 and 21.3, respectively. There was no significant difference in failure by size cohort. Median OS was 33 m, with 1-year OS at 75%. When analyzed by cohort, OS significantly declined with increasing size (p = 0.0421) CONCLUSION: Local control and toxicity with SF-SBRT for tumors > 3cm is comparable to that seen with smaller tumors treated on randomized trials.

Cardiac and Great Vessel Toxicity with Single Fraction Stereotactic Body Radiotherapy in Early-Stage Lung Cancer

PURPOSE/OBJECTIVE(S)

The relationship between thoracic radiotherapy and cardiovascular (CV) morbidity is an area of interest. When considering stereotactic body radiotherapy (SBRT) in the management of early-stage lung cancer, reports suggest CV dose may correlate with survival. To study this association for single fraction SBRT (SF-SBRT), we performed a retrospective review of patients treated at our institution assessing for associations between this dose schedule and CV toxicity.

MATERIALS/METHODS

For the interval 2010-2022, we surveyed our IRB-approved prospective registry for SF-SBRT patients with tumors within 1 cm of the heart or any of the great vessels (GVs). Distance of the tumor to these structures was stratified as: directly contacting, within 0.5 cm, from 0.5-1 cm, or > 1 cm. Medical records were reviewed post-SBRT for CV events including: myocardial infarction (MI), heart failure (HF), structural heart damage (valvular or wall abnormalities), vascular damage (aneurysm, dilation, other abnormalities), hemoptysis, and arrhythmia which were correlated with lesion location and history.

RESULTS

Four hundred four patients treated with SF-SBRT to 34 Gy in 1 fraction were identified. 35 patients (8.7%) had 36 lesions within 1 cm of the heart or GVs. 68.6% of patients were female and 74.3% were Caucasian. The median age was 72.5 years (range: 60-91), median Charlson comorbidity score was 6, median KPS was 80, and median ASCVD score was 21.0%. 33 patients had a smoking history with a median of 50 pack years. 12 patients (34.3%) had an arrhythmia prior to SBRT, 5 (14.2%) had prior HF, and 9 (25.7%) had prior MI or CV disease. All cases were non-small cell lung cancer or radiographic malignancy with 1 case of small cell lung cancer. Median tumor size was 1.6 cm. 91.4% of patients had stage I disease. Median follow-up was 2.26 years (0.37-4.0). Seven lesions (19.4%) were abutting the heart or GVs, 14 (38.9%) were within 0.5 cm, and 15 (41.7%) were from 0.5-1 cm. 54 events were observed with a median of 1 event per patient (0-5). The most common events were arrhythmia (15), vascular damage (9), structural damage (12), heart failure (9), and MI (6). The most commonly associated vascular structure was the aortic arch, while the most commonly involved substructures of the heart were the right atrium and left ventricle. 12 events occurred in the direct contact group, 17 in the < 0.5 cm group, and 25 in the 0.5-1 cm group. Patients with heart associated lesions accounted for 8 events, while those with vessel associated tumors accounted for 46.

CONCLUSION

While cardiac events are relatively common in the medically inoperable SBRT population, they did not appear to be more common with tumors directly contacting major cardiovascular structures than for those with some separation. Most events could be attributed to medical causes other than SBRT. Further study is needed to clarify the potential role of radiation in events without direct explanation.

NRG-RTOG 1106/ACRIN 6697: A phase IIR trial of standard versus adaptive (mid-treatment PET-based) chemoradiotherapy for stage III NSCLC—Results and comparison to NRG-RTOG 0617 (non-personalized RT dose escalation)

8548

Background: NRG-RTOG 0617 (R0617) found that non-personalized dose escalation of radiotherapy (RT) with concurrent chemotherapy was deleterious. NRG-RTOG 1106/ACRIN 6697 (R1106) studied adaptive chemoradiotherapy, using tumor and patient individualized RT dose intensification simultaneously with field reduction, based upon mid-treatment FDG-PET. Methods: The control arms of both studies used 60 Gy (+ weekly carboplatin/paclitaxel). The investigational arm of R0617 used 74 Gy in 37 fractions, with no field/dose adaptation, while R1106 used mid-treatment FDG-PET (after ̃40 Gy) to design an individualized dose adaptive RT plan with daily-fraction size 2.2 to 3.8 Gy (up to 80.4 Gy/30 fractions), based upon a model of isotoxic lung risk. Nearly all (93%) patients had IMRT. No patients had consolidation immunotherapy. The primary endpoint for R1106 was local-regional-progression freedom (LRPF) assessed by central review. Other endpoints reported here were survival, toxicity, and institution-defined local/regional control. Results: From 2012-2017, 127 patients were enrolled to R1106 (43 in the standard and 84 in the adaptive arms), with a median follow-up of 3.6 years. The median actual RT dose in the adaptive arm was 71 Gy (Q1-Q3 68-76 Gy). The 2-year LRPF was 59.5% versus 54.6% (p=0.66) for standard versus adaptive RT; the 3-year survival rates were 49.1% versus 47.5% (p=0.80). An exploratory analysis of 2-year in-field local primary tumor control and local-regional tumor control (institution-assessed) were 58.5% and 55.6% for standard RT, and 75.6% and 66.3% for adaptive RT, respectively. As shown in the table, there were no significant differences in cardiac or esophageal adverse events between the two arms; the adaptive RT arm had more Grade 3+ respiratory events (23.8% versus 14.3%). Conclusions: NRG-RTOG1106 did not meet its primary endpoint of demonstrating improved LRPF. Unlike R0617, there was no suggestion of a detrimental effect of adaptive dose-intensified RT on survival and cardiac events. Studies to refine personalized RT, especially in the immunotherapy era, should be considered. Outcome comparison between R0617 and R1106. Clinical trial information: NCT01507428. [Table: see text]

A phase I safety and feasibility study of neoadjuvant chemoradiation plus pembrolizumab followed by consolidation pembrolizumab in resectable stage IIIA non-small cell lung cancer

9009

Background: Patients (pts) with resectable stage IIIA non-small cell lung cancer (NSCLC) have high rates of recurrence despite concurrent chemoradiation (CRT) followed by surgery. Immune checkpoint inhibitor consolidation has improved outcomes in unresectable stage III pts. Here we report the addition of concurrent neoadjuvant pembrolizumab (P) to CRT in stage IIIA patients to determine the safety and feasibility of this approach. Methods: Pts with stage IIIA NSCLC deemed resectable by a thoracic surgeon received neoadjuvant CRT consisting of cisplatin, etoposide, and concurrent P (200mg every 3 weeks x 3) with 45 Gy in 25 fractions. Pts without progression underwent resection followed by 6 months of consolidation P. The primary objective was feasibility and safety (defined as ≤30% grade 3 or higher pulmonary toxicity or any grade 4/5 nonhematologic toxicity). Ten pts were to be enrolled in Part 1, and if 2 or fewer pts had events then an additional 10 pts were to be enrolled. Secondary objectives were progression free survival (PFS), overall response rate (ORR), and pathologic complete response rate (pCR). Results: The median age of 9 enrolled pts was 66 years (range 49-76). 67% were female. 8 pts were assessable for radiographic response with an ORR of 75%. One pt came off study for progression prior to surgery and one had pleural metastases found during surgery so resection was aborted. Six pts underwent complete resection with a pCR rate of 67% (4/6). Consolidation P was started on 4 pts, with 3 completing treatment and 1 declined further treatment after 3 cycles. Median follow-up is 19.6 months and median PFS has not been reached. None of the patients who underwent resection have recurred. Serious adverse events were reported in all 9 pts with most significant being 2 grade 5 events: 1 due to pneumocystis pneumonia after resection but prior to consolidation, and 1 due to cardiac arrest during the neoadjuvant phase. Grade 3 events included 1 episode each of pneumonitis, bronchopleural fistula, acute kidney injury, colon perforation, and febrile neutropenia. Conclusions: The addition of P to neoadjuvant CRT in resectable stage IIIA pts resulted in a high pCR rate at resection. Although the relationship between grade 5 events and the addition of P was not clear, the stopping rule for infeasibility was met. As other larger studies are underway, the trial was halted rather than amended. This investigator initiated trial was funded by Merck. Clinical trial information: NCT02987998.

Initial reporting of NRG-LU001 (NCT02186847), randomized phase II trial of concurrent chemoradiotherapy (CRT) +/- metformin in locally advanced Non-Small Cell Lung Cancer (NSCLC)

8502

Background: Metformin, a diabetes agent that inhibits mitochondria complex I, enhances radiotherapy and chemotherapy responses in pre-clinical models of NSCLC. NRG-LU001 examined whether metformin can improve outcomes of curative CRT in locally advanced (LA)-NSCLC. Methods: The primary endpoint of this trial was 1-year progression free survival (PFS). Unresected, non-diabetic, stage IIIA/B NSCLC patients were randomized (1:1) to either carboplatin-paclitaxel chemotherapy concurrent with chest RT (60Gy), followed by consolidation carboplatin-paclitaxel chemotherapy (Control Arm) or the same and oral metformin (2000mg daily) during cytotoxic therapy (Experimental Arm). PFS and overall survival (OS) were estimated with the Kaplan-Meier method; time to local-regional progression (TTLRP), time to distant metastasis (TTDM) were estimated using the cumulative incidence method. Adverse events (AEs) were graded with CTCAE v.4.0. Results: Between Aug.2014 and Dec.2016, 170 patients were accrued. Analysis was planned at 102 PFS events (Feb. 2019). There was no significant difference in rates or grade of toxicity between the two arms. 1- and 2-year PFS was 60.4% (95% CI: 48.5, 70.4) and 40.1% (95% CI: 29.0, 51.0) in Control vs 51.3% (95% CI: 39.8, 61.7) and 34.5% (95% CI: 24.2, 45.1) in the Metformin arm (multivariable Cox proportional HR=1.20 (95% CI: 0.81, 1.78), p=0.36). OS at 2 years was 65.4% (95% CI: 53.5, 75.0) for Control vs 64.9% (95% CI: 53.1, 74.5) for the Metformin arm (HR=1.03 (95% CI: 0.64, 1.68)), while deaths due to disease were 90% vs 71%, respectively. No significant differences were found for TTLRP or TTDM. Conclusions: NRG-LU001 center reported outcomes show that oral daily metformin was well-tolerated in combination with CRT treatment for LA-NSCLC. However, metformin did not improve PFS and OS and did not alter the rates of local-regional failure or distant metastasis. Acknowledgements: TT and HS are Co-Principal Investigators. This project was supported by National Cancer Institute (NCI) grants: U10CA180868 (NRG Oncology Operations), U10CA180822 (NRG SDMC), UG1CA189867 (NCORP), U24CA180803 (IROC). Clinical trial information: NCT02186847.

Identifying delays in care for patients with NSCLC using value-stream mapping

136

Background: Value-Stream Mapping (VSM) was employed to evaluate non-value added activities focused on minimizing time between pathological diagnosis and first treatment (Time-To-Treat or TTT). Objective is to identify unnecessary delays in care for NSLC patients treated at a large academic medical center. Methods: A total of 253 patient records were examined between 1/15/2015 and 7/19/2016 and divided into stages: Stage I (Non-Surgical), Stage I-II (Surgical), Stage III, and Stage IV. Selection criteria required a min. of 50 patients/stage, including internally and externally diagnosed patients. A VSM was developed for each stage. Spreadsheets were used to detail dates and sequences of events, including consults, E&M visits, imaging, procedures, and testing. Results: Overall TTT results by stage (median days) are as follows: Stage I (Non-Surgical) = 46 days (n = 55), Stage I-II (Surgical) = 35 days, n = 50), Stage III = 34 days (n = 71), Stage IV = 19 days (n = 77). Consults were reviewed among 4 specialties (Med/Onc, Rad/Onc, Surgical, Pulmonary), revealing Pulmonary Consults most common regardless of stage, 38%, 40%, 49%, 29%, respectively. It was found consults among specialties were rarely coordinated (stage III: 11/70 patients had consults same day between 2 specialties). Bronchoscopy procedures were most common method of Dx; sampling (n = 60, all stages) revealed MD orders are placed within 1 median day for each stage (15% ≥ 5days), but lead time to procedure ranged 7-12 median days depending on stage. Comorbidities for surgical patients (n = 46) were reviewed and found TTT delays correlates with number of comorbidities and FEV1 test results. Interventions included weekly, multi-disciplinary identification and review of patients across the 4 specialties, development of a TTT visual dashboard, and creation of communication standards across specialties. Conclusions: A VSM will identify areas where excessive delays occur. Opportunities exist to combine activities (same-day appointments/consults), reduce delays between activities, and/or improve communication. Decision-making can be accelerated when time between events (consults, staging, procedures, and tests) is minimized, regardless of diagnosis origin.

Outcomes of definitive radiotherapy (dRT) and chemo-radiotherapy (dCRT) for loco-regionally confined (LRC) adenocarcinoma (ACA) of the esophagus and gastro-esophageal junction (E/GEJ)

114

Background: Surgery is the cornerstone of curative intent therapy for patients with ACA of the E/GEJ. Many patients (pts) with LRC disease are medically unsuitable for resection, and thus alternative treatment strategies are required. Definitive CRT is a standard of care for esophageal squamous cell carcinoma, but less is known regarding the outcomes for ACA of the E/GEJ. Methods: Through the Cleveland Clinic tumor registry, and under an IRB approved protocol, pts with LRC (clinical stage I-III, AJCC 7th) ACA of the E/GEJ treated with either dRT or dCRT between 7/04 and 12/14 were identified. Overall survival (OS) from the date of diagnosis was the primary endpoint. In univariate analysis, Cox proportional hazard analysis was used to identify risk factors for mortality. On multivariable analysis, stepwise Cox proportional hazard analysis with variable entry criterion p≤0.10 and variable retention criteria p≤0.05 was used to identify risk factors for mortality. Results: From 7/04 to 12/14, 155 pts received definitive non-operative treatment (103 dCRT, 52 dRT). Clinical stage I disease was present in 20 (13.2%); stage II in 40 (26.5%) and stage III in 91 (60.3%) of the pts. Pts who received dCRT were younger (67 v 74 years, p<0.001) and had more advanced clinical stage (p=0.026). Loco-regional recurrence / persistence was the predominant form of treatment failure occurring in 60% of pts (dCRT 54.3%, dRT 71.2%, p=0.044). With a median follow-up of 34.9 months (range 2.0-107.1), the median OS was 17.3 months (15.6m dCRT, 19.8m dRT, p=0.40) and the projected 5 year OS was 11.5% (16.1% dCRT, 4.0% dRT, p = 0.030). On univariable and multivariable analysis, a worse ECOG performance status, increasing clinical T descriptor, and increasing clinical N descriptor were prognostic for a worse OS. After adjusting for these variables, dRT was associated with a worse OS [dRT/dCRT HR 1.79 (1.20-2.68) p=0.005]. Conclusions: Definitive RT/CRT for LRC ACA of the E/GEJ is associated with poor OS. Long-term survival is nonetheless possible in a small number of pts and appears more likely after dCRT.

Pathologic and clinical outcomes in cT2N0 esophageal cancer: A cohort study

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Background: The management of clinically staged T2N0 (cT2N0) esophageal cancer remains controversial and clinical staging can be inaccurate. We evaluated concordance between clinical and pathologic staging as well as outcomes in a cohort study of patients initially staged as cT2N0. Methods: We conducted a cohort study of consecutive patients with esophageal cancer staged as cT2N0 after imaging (CT, PET scans) and endoscopic ultrasound, who underwent surgical resection and were followed at the Cleveland Clinic from Jan 2000 to Jun 2014. Clinical, chemotherapy (CT), radiation (RT), pathologic, and survival details were evaluated. For statistically significant associations, adjusted hazard ratios (HR) with 95% confidence intervals (CI) and 2-sided p-values are presented. Results: The study population comprised 66 consecutive patients with cT2N0 esophageal cancer. Median age was 60 years; 76% were male; 97% were Caucasian. Gastroesophageal junction was the primary site in 56%; distal esophagus in 29%; middle esophagus in 14%; histology was adenocarcinoma in 62 (94%) cases. 20 patients received preop treatment (Rx): CT+RT (15), CT (5). In patients without preoperative Rx (n = 46, 70%), pathologic staging was > T2N0 in 54% (n = 25; T3 = 17, T4 = 1, N+ = 20), < T2N0 in 37% (n = 17), and T2N0 in 9% (n = 4). No < T2N0 or T2N0 patient received postop Rx. Of 25 > T2N0, 15 received postop Rx: CT+RT (14), CT (1). 5-fluourouracil-cisplatin was the most common CT regimen. Median overall survival (mOS) after 7 years of median follow-up was: overall, 48 mths (34 deaths, 52%); < T2N0/T2N0, 93 mths; > T2N0 with postop Rx, 69 mths; > T2N0 without postop Rx, 15 mths (p > 0.05 for comparison). Only node-positive disease on pathology was associated with mortality (mOS for N+ vs. N- was 28 vs. 118 mths, HR for mortality = 2.74, 95% CI = 1.30-5.76, p = 0.008); T-stage, surgical margins, timing or type of therapy were not. Conclusions: Clinical staging of cT2N0 esophageal cancer is concordant with pathologic staging in less than 10% of patients; a majority are under-staged. Strong consideration should be given to pre- or post-operative treatment in this population. Improvements in clinical staging approaches are urgently needed to avoid over- and under-treatment in this setting.

The impact of persistent dysphagia (PD) after induction chemotherapy in patients with locoregionally advanced (LRA) adenocarcinoma (ACA) of the esophagus and gastroesophageal junction (E/GEJ) receiving a trimodality treatment regimen

160

Background: For patients with LRA ACA of the E/GEJ who receive pre-operative therapy, advanced pathologic stage at surgery is strongly associated with recurrence and death. Identification of such patients prior to resection, however, is problematic. Given the morbidity of esophageal resection, alternative treatment strategies may be desirable in this patient population. Methods: Between 2/08 and 1/12, 60 evaluable patients with LRA ACA of the E/GEJ enrolled in single arm phase II trial of induction chemotherapy, surgery, and post-operative chemoradiotherapy. A clinical stage of T3, N1 or M1a (AJCC 6th) was required for eligibility. Induction chemotherapy with epirubicin 50mg/m2 d1, oxaliplatin 130mg/m2 d1, and fluorouracil 200mg/m2/day continuous infusion for 3 weeks, was given every 21 days for 3 courses and was followed by surgical resection. Adjuvant CRT consisted of 50-55Gy @ 1.8-2.0 Gy/d and 2 courses of cisplatin (20mg/m2/d) and fluorouracil (1000mg/m2/d) given as 96 hour infusions during weeks 1 and 4 of radiotherapy. Dysphagia was assessed at baseline and after induction chemotherapy. Updated results as of March 2014 are presented. Results: Of the 60 evaluable patients enrolled, 54 completed induction therapy and underwent surgery. Of these 54 patients, 44 patients experienced complete resolution of dysphagia, while 10 patients had persistent symptoms. PD was associated with worse distant metastatic control [HR 3.48 (1.43 – 8.43), p=0.006], recurrence free survival [HR 3.04 (1.34 – 6.92), p=0.008], and overall survival [HR 3.31 (1.43 – 7.66), p=0.005]. PD was associated with more advanced pathologic T-descriptor (pT) (p=0.048) and N-descriptor (pN) (p=0.002), a greater median number of involved lymph nodes (3 v 1, p=0.003), and greater residual tumor viability (p=0.05). No patients with PD had pT0-T2 or pN0 disease. Of the 9 patients with pN3 disease, 5 (56%) had PD. Conclusions: PD after induction chemotherapy is associated with more advanced pathologic stage and inferior outcomes. These patients may require alternative treatment strategies. Clinical trial information: NCT00601705.

The relationship between pathologic nodal disease and residual tumor viability (RV) in patients with locoregionally advanced (LRA) adenocarcinoma (ACA) of the esophagus and gastroesophageal junction (E/GEJ) receiving induction chemotherapy, surgery, and postoperative chemoradiotherapy (CRT)

165

Background: A complete pathologic response to induction CRT has been identified as a favorable prognostic factor for patients with LRA ACA of the E/GEJ. Less is known, however, about the impact of pathologic regression after induction chemotherapy. Methods: Between 2/08 and 1/12, 60 evaluable patients with ACA of the E/GEJ enrolled in a phase II trial of induction chemotherapy, surgery, and post-operative CRT. Eligibility required a clinical stage of T3 or N1 or M1a (AJCC 6th). Induction chemotherapy with epirubicin 50mg/m2 d1, oxaliplatin 130mg/m2 d1, and fluorouracil 200mg/m2/day continuous infusion for 3 weeks, was given every 21 days for 3 courses and was followed by surgical resection. Adjuvant CRT consisted of 50-55Gy @ 1.8-2.0 Gy/d and 2 courses of cisplatin (20mg/m2/d) and fluorouracil (1000mg/m2/d) over 4 days during weeks 1 and 4 of radiotherapy. RV was defined as the amount of remaining tumor in relation to acellular mucin pools and scarring. Results: Of the 60 evaluable patients, 54 completed induction therapy and underwent curative intent surgery. The Kaplan-Meier (KM) projected 3 year OS for patients with pathologic N0 (n=20), N1 (n=12), N2 (n=13), and N3 (n=9) disease is 73%, 57%, 35%, and 0% respectively (p<0.001). The KM projected 3 year OS of patients with low (0-25%, n=19), intermediate (26-75%, n=26), and high (>75%, n=9) RV was 67%, 42%, and 17% respectively (p=0.004). On multivariable analysis, both the pN descriptor and RV were independently prognostic for OS. In patients with less nodal dissemination (N0/N1), RV was prognostic for OS [3yr OS 85% (0-25% viable) v 51% (>25% viable), p=0.028]. Outcomes were poor, however, for patients with advanced nodal disease (N2/N3) regardless of RV [3yr OS 20% (0-25% viable) v 21% (>25% viable), p=0.55]. Conclusions: RV and the pN descriptor after induction chemotherapy are independent pathologic prognostic factors for OS in patients with LRA ACA of the E/GEJ. Patients with extensive nodal disease, however, have poor outcomes irrespective of viability. Clinical trial information: NCT00601705.

Clinicopathologic features and treatment outcomes of patients with human epidermal growth factor receptor 2-positive adenocarcinoma of the esophagus and gastroesophageal junction

Human epidermal growth factor receptor 2 (HER2) is overexpressed in 21% of gastric and 33% of gastroesophageal junction (GEJ) adenocarcinomas. Trastuzumab has been approved for metastatic HER2-positive gastric/GEJ cancer in combination with chemotherapy. This retrospective analysis was undertaken to better define the clinicopathologic features, treatment outcomes, and prognosis in patients with HER2-positive adenocarcinoma of the esophagus/GEJ. Pathologic specimens from 156 patients with adenocarcinoma of the esophagus/GEJ treated on clinical trials with chemoradiation and surgery were tested for HER2. Seventy-six patients also received 2 years of gefitinib. Baseline characteristics and treatment outcomes of the HER2-positive and negative patients were compared both in aggregate and separately for each of the two trials. Of 156 patients, 135 had sufficient pathologic material available for HER2 assessment. HER2 positivity was found in 23%; 28% with GEJ primaries and 15% with esophageal primaries (P= 0.10). There was no statistical difference in clinicopathologic features between HER2-positive and negative patients except HER2-negative tumors were more likely to be poorly differentiated (P < 0.001). Locoregional recurrence, distant metastatic recurrence, any recurrence, and overall survival were also statistically similar between the HER2-positive and the HER2-negative groups, in both the entire cohort and in the gefitinib-treated subset. Except for tumor differentiation, HER2-positive and negative patients with adenocarcinoma of the esophagus and GEJ do not differ in clinicopathologic characteristics and treatment outcomes. Given the demonstrated benefit of trastuzumab in HER2-positive gastric cancer and the similar incidence of HER2 overexpression in esophageal/GEJ adenocarcinoma, further evaluation of HER2-directed therapy in this disease seems indicated.

Correlation between toxicity and outcome after multimodality therapy of locoregionally advanced (LRA) adenocarcinoma (ACA) of the esophagus (E) and gastroesophageal junction (GEJ)

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Background: Multiagent concurrent chemoradiation (CRT) and surgery is a standard curative-intent approach for patients (pts) with LRA ACA of the E/GEJ. This single institution retrospective analysis examined whether toxicities occurring during induction chemoradiation (ICRT) were independently prognostic for outcome. Methods: Between 11/99 and 7/06, 152 pts with T3, N1 or M1a ACA of the E/GEJ were entered onto one of two Cleveland Clinic trials. ICRT with 96 hour infusions of cisplatin (20mg/m2/d) and fluorouracil (1000mg/m2/d) beginning on day 1 of radiation (30Gy@1.5Gy bid), was followed by surgery and identical post-operative CRT. 75 pts also received 2 years of oral gefitinib. Multivariable Cox analysis was used to identify prognostic factors for overall survival (OS), freedom from recurrence (FFR), locoregional (LRC) and distant metastatic control (DMC). Both clinical features (including demographics, tumor characteristics, symptomatic and pathologic response), and ICRT- related toxicities (including nausea/vomiting, mucositis/dysphagia, neutropenia, thrombocytopenia, neutropenic fever and any unplanned hospitalization) were analyzed. Results: Of the 152 pts enrolled, resection proved possible in 138 (91%). With a median follow-up of 90 (range 57-126) months, the 5-year Kaplan-Meier projected OS is 22%, FFR 24%, DMC 27% and LRC 69%. As expected, in multivariable analysis, earlier clinical stage disease and a pathologic and symptomatic response to ICRT all proved favorable for treatment outcomes. In addition, the development of grade 3-4 (vs. grade 0-2) mucositis and/or dysphagia during ICRT was a significant risk factor for distant recurrence [HR 2.62 (1.34-5.12), p=0.005]; any recurrence [HR 2.08 (1.08-4.00), p=0.027] and death [HR 2.00 (1.07-3.74), p=0.031]. Neutropenic fever was also correlated with distant recurrence [HR 1.82 (1.03-3.22, p=0.039] and any recurrence [HR 2.19 (1.23-3.90) p=0.007]. Conclusions: Neutropenic fever and the development of grade 3-4 mucositis and/or dysphagia during ICRT are independently associated with worse outcomes after multimodality therapy for E/GEJ ACA.

Relationship between treatment duration and outcomes in patients receiving concurrent chemoradiotherapy (CCRT) and surgery for locoregionally advanced (LRA) esophageal and gastroesophageal junction (E/GEJ) adenocarcinoma (ACA)

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Background: Retrospective studies in breast, colon, and head and neck cancer have suggested that delays in administration of adjuvant chemotherapy result in inferior outcomes. We explore this question in patients with LRA E/GEJ ACA. Methods: From 11/99 to 7/06, 152 patients with cT3, N1, or M1a disease were enrolled on one of two clinical trials at the Cleveland Clinic. Two courses of CCRT consisting of 30Gy radiation (@1.5Gy BID) with continuous infusion cisplatin (20mg/m2/day x 4 days) and 5Fu (1000mg/m2/d x 4 days) were given both before and after surgical resection. In the second trial, 75 patients also received gefitinib during the 4 week induction and for a total of two years postoperatively. Using recursive partitioning analysis (RPA), we retrospectively explored the relationship between treatment duration and loco-regional control (LRC), distant metastatic control (DMC), freedom from recurrence (FFR), and overall survival (OS) in the 115 patients (76%) who completed all treatment. Outcomes were estimated using the Kaplan-Meier method and compared among groups using the log-rank test. Results: RPA analysis identified three groups of patients: 19 patients in whom resection occurred ≤45 days from the start of CCRT to resection (short treatment), 63 patients who underwent resection >45 days from the start of CCRT and required <50 days to complete treatment after surgery (intermediate treatment), and 33 patients who underwent resection >45 days from the start of CCRT but required ≥50 days to complete treatment after surgery (prolonged treatment). With a median follow-up of 90 (range 57-126) months, we found that patients with shorter treatment times had better 5 year DMC [64% (short) v 26% (intermediate) v 16% (prolonged); p=0.004], FFR [57% (short) v 23% (intermediate) v 16% (prolonged); p=0.015)], and OS [42% (short) v 30% (intermediate) v 12% (prolonged); p=0.08]. LRC was not different between the groups. Conclusions: Treatment delays in patients receiving multimodality therapy for LRA E/GEJ ACA may result in a greater risk of recurrence and decreased survival.

Clinical neurological outcome and quality of life among patients with limited small-cell cancer treated with two different doses of prophylactic cranial irradiation in the intergroup phase III trial (PCI99-01, EORTC 22003-08004, RTOG 0212 and IFCT 99-01)

BACKGROUND

We recently published the results of the PCI99 randomised trial comparing the effect of a prophylactic cranial irradiation (PCI) at 25 or 36 Gy on the incidence of brain metastases (BM) in 720 patients with limited small-cell lung cancer (SCLC). As concerns about neurotoxicity were a major issue surrounding PCI, we report here midterm and long-term repeated evaluation of neurocognitive functions and quality of life (QoL).

PATIENTS AND METHODS

At predetermined intervals, the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 and brain module were used for self-reported patient data, whereas the EORTC-Radiation Therapy Oncology Group Late Effects Normal Tissue-Subjective, Objective, Management, Analytic scale was used for clinicians' assessment. For each scale, the unfavourable status was analysed with a logistic model including age, grade at baseline, time and PCI dose.

RESULTS

Over the 3 years studied, there was no significant difference between the two groups in any of the 17 selected items assessing QoL and neurological and cognitive functions. We observed in both groups a mild deterioration across time of communication deficit, weakness of legs, intellectual deficit and memory (all P < 0.005).

CONCLUSION

Patients should be informed of these potential adverse effects, as well as the benefit of PCI on survival and BM. PCI with a total dose of 25 Gy remains the standard of care in limited-stage SCLC.

Implant volume as a prognostic variable in brachytherapy decision-making for malignant gliomas stratified by the RTOG recursive partitioning analysis

PURPOSE

When an initial retrospective review of malignant glioma patients (MG) undergoing brachytherapy was carried out using the Radiation Therapy Oncology Group (RTOG) recursive partitioning analysis (RPA) criteria, it revealed that glioblastoma multiforme (GBM) cases benefit the most from implant. In the present study, we focused exclusively on these GBM patients stratified by RPA survival class and looked at the relationship between survival and implanted target volume, to distinguish the prognostic value of volume in general and for a given GBM class.

METHODS AND MATERIALS

Between 1991 and 1998, 75 MG patients were treated with surgery, external beam radiation, and stereotactic iodine-125 (I-125) implant. Of these, 53 patients (70.7%) had GBMs, with 52 (98%) having target volume (TV) data for analysis. Stratification by RPA criteria showed 12, 26, 13, and 1 patients in classes III to VI, respectively. For analysis purposes, classes V and VI were merged. There were 27 (51.9%) male and 25 (48.1%) female patients. Mean age was 57.5 years (range 14-79). Median Karnofsky performance status (KPS) was 90 (range 50-100). Median follow-up time was 11 months (range 2-79).

RESULTS

At analysis, 18 GBM patients (34.6%) were alive and 34 (65.4%) were dead. Two-year and 5-year survivals were 42% and 17.5%, respectively, with a median survival time (MST) of 16 months. Two-year survivals and MSTs for the implanted GBM patients compared to the RTOG database were as follows: 74% vs. 35% and 28 months vs. 17.9 months for class III; 32% vs. 15% and 16 months vs. 11.1 months for class IV; 29% vs. 6% and 11 months vs. 8.9 months for class V/VI. Mean implanted TV was 15.5 cc (range 0.8-78), which corresponds to a spherical implant diameter of 3.1 cm. Plotting survival as a function of 5-cc TV increments suggested a trend toward poorer survival as the implanted volume increases. The impact of incremental changes in TV on survival within a given RPA class of GBMs was compared to the RTOG database. Looking at absolute differences in MSTs: for classes III and IV, there was little effect of different TVs on survival; for class V/VI, a survival benefit to implantation was still seen at the target volume cutoff (TV > 25 cc). Within a given RPA class, no significant differences were found within class III; for class IV, the most significant difference was at 10 cc (p = 0.05); and for class V/VI, at 20 cc (p = 0.06).

CONCLUSION

For all GBM patients, an inverse relationship between implanted TV size and median survival is suggested by this study. However, when GBM patients are stratified using the RTOG's RPA criteria, the prognostic effect of implant volume disappears within each RPA survival class. At the critical volume of 25 cc, which approximates an implant of 5-cm diameter (upper implantation limit of many CNS brachytherapy protocols), the "poorest" prognosis GBM patients stratified by RPA still demonstrate a survival benefit with implant. We suggest that any GBM patient meeting brachytherapy recognized size criteria be considered for I-125 implant.

Using treatment interruptions to palliate the toxicity from concurrent chemoradiation for limited small cell lung cancer decreases survival and disease control

BACKGROUND AND PURPOSE

We analyzed the impact on survival outcomes of treatment interruptions due to toxicity arising during the concurrent phase of chemotherapy/radiotherapy (ChT/RT) for our limited-stage small-cell cancer (LSCLC) population over the past 10 years.

MATERIALS AND METHODS

From 1989 to 1999, 215 patients received treatment for LSCLC, consisting of six cycles of alternating cyclophosphamide/doxorubicin or epirubicin/vincristine (CAV; CEV) and etoposide/cisplatin (EP). Thoracic RT was started with EP at either the second or third cycle (85% of patients). RT dose was either 40 Gy in 15 fractions over 3 weeks or 50 Gy in 25 fractions over 5 weeks, delivered to a target volume encompassing gross disease and suspected microscopic disease with a 2 cm margin. Treatment breaks arising during concurrent ChT+RT were used to manage severe symptomatic or hematologic toxicities. We used the interruptions in thoracic RT as the 'marker' for any concurrent break and measured 'break duration' by the total length of time (in days) RT was interrupted, since that also signaled that ChT could be re-initiated. Patient results were analyzed for the impact of interruptions/treatment prolongation on overall and disease-free survival.

RESULTS

For all patients, 2-year and 5-year overall and disease-specific survivals were 22.7 and 7.2, 27.6 and 9.3%, respectively; overall and disease-specific median survivals were 14.7 months each. A total of 56 patients (26%) had treatment breaks due to toxicity. Hematologic depression caused the majority of breaks (88%). The median duration of breaks was 5 days (range 1-18). Patients with and without interruptions were compared for a range of prognostic factors and were not found to have any significant differences. Comparing interrupted/uninterrupted courses, median survivals were 13.8 versus 15.6 months, respectively, and 5-year overall survivals were 4.2 versus 8.3%, respectively. There was a statistical difference between overall survival curves which favored the uninterrupted group (P=0.01). When comparing a series of prognostic variables, multivariable analysis found that the most significant factor influencing survival in the present study was the presence of treatment breaks (P=0.006). There was a trend for development of any recurrence in the patients with breaks (P=0.08). When controlling for the use of prophylactic cranial irradiation (PCI) in the two groups, the rate of failure in the chest was higher in the patients with RT breaks (58 vs. 33%). The rate of failure in the brain was dependent on the use of PCI only.

CONCLUSIONS

Interruptions in treatment to palliate the toxicity from concurrent chemoradiation result in poorer local control and decreased survival.

HIV complicates the management of oncological emergencies: a case involving the superior vena cava syndrome

An association exists between human immunodeficiency virus (HIV) and an increased incidence of lung cancer. Superior vena cava syndrome (SVCS) is an oncological emergency seen in the presence of chest tumours. We report on an otherwise well HIV-positive male who presented with SVCS due to lung cancer. He was commenced on dexamethasone and radiotherapy with curative intent. Treatment was complicated by accelerated steroid- and radiation-induced morbidity. The patient died of disseminated aspergillosis after receiving 27 of 35 planned radiotherapy fractions. The management of SVCS in those with HIV is challenging and requires the judicious use of steroids, antifungal prophylaxis and palliative radiotherapy doses.

Use of the RTOG recursive partitioning analysis to validate the benefit of iodine-125 implants in the primary treatment of malignant gliomas

PURPOSE

To date, numerous retrospective studies have suggested that the addition of brachytherapy to the conventional treatment of malignant gliomas (MG) (surgical resection followed by radiotherapy +/- chemotherapy) leads to improvements in survival. Two randomized trials have suggested either a positive or no survival benefit with implants. Critics of retrospective reports have suggested that the improvement in patient survival is due to selection bias. A recursive analysis by the RTOG of MG trials has stratified MG patients into 6 prognostically significant classes. We used the RTOG criteria to analyze the implant data at Wayne State University to determine the impact of selection bias.

METHODS AND MATERIALS

Between July 1991 and January 1998, 75 patients were treated with a combination of surgery, radiotherapy, and stereotactic I-125 implant as primary MG management. Forty-one (54.7%) were male; 34 (45.3%) female. Median age was 52 years (range 4-79). Twenty-two (29.3%) had anaplastic astrocytoma (AA); 53 (70.7%), glioblastoma multiforme (GBM). Seventy-two patients had data making them eligible for stratification into the 6 RTOG prognostic classes (I-VI). Median Karnofsky performance status (KPS) was 90 (range 50-100). There were 14, 0, 14, 31, 12, and 1 patients in Classes I to VI, respectively. Median follow-up time for AA, GBM, and any surviving patient was 29, 12.5, and 35 months, respectively.

RESULTS

At analysis, 29 (40.3%) patients were alive; 43 (59.7%), dead. For AA and GBM patients, 2-year and median survivals were: 58% and 40%; 38 and 17 months, respectively. For analysis purposes, Classes I and II, V and VI were merged. By class, the 2-year survival for implanted patients compared to the RTOG data base was: III--68% vs. I--76%; III--74% vs. 35%; IV--34% vs. 15%; V/VI--29% vs. V--6%. For implant patients, median survival by class was (in months): I/II--37; III--31; IV--16; V/VI--11.

CONCLUSION

When applied to MG patients receiving permanent I-125 implant, the criteria of the RTOG recursive partitioning analysis are a valid tool to define prognostically distinct survival groups. As reflected in the RTOG study, a downward survival trend for the implant patients is seen from "best to worse" class patients. Compared to the RTOG database, median survival achieved by the addition of implant is improved most demonstrably for the poorer prognostic classes. This would suggest that selection bias alone does not account for the survival benefit seen with I-125 implant and would contradict the notion that the patients most eligible for implant are those gaining the most benefit from the treatment. In light of the contradictory results from two randomized studies and given the present results, further randomized studies with effective stratification are required since the evidence for a survival benefit with brachytherapy (as seen in retrospective studies) is substantial.

Hyperbaric oxygen corrects sacral plexopathy due to osteoradionecrosis appearing 15 years after pelvic irradiation

In 1982, a 55-year-old woman was treated by total cystectomy and adjuvant radiotherapy/chemotherapy for a leiomyosarcoma of the bladder. Fifteen years later she presented with symptoms and signs of sacral plexopathy. Investigations revealed osteoradionecrosis of the sacrum. Hyperbaric oxygen therapy (HBO2) was instituted and progressive resolution of the neurological complaints followed. HBO2 should be considered when managing late-onset sequelae in previously irradiated patients.

Preoperative radiation with concurrent 5-fluorouracil continuous infusion for locally advanced unresectable rectal cancer

BACKGROUND AND PURPOSE

To determine the percentage of complete responders and the resectability rate for patients with locally advanced carcinoma of the rectum treated by 5-fluorouracil (5-FU) infusional chemotherapy and pelvic radiation.

MATERIALS AND METHODS

Between October 1992 and June 1996, 29 patients with a diagnosis of locally advanced unresectable rectal cancer received preoperative 5 FU by continuous intravenous infusion at a dose of 225 mg/m2/day concurrent with pelvic radiation (median 54 Gy/28 fractions). All patients were clinical stage T4 on the bases of organ invasion or tumor fixation. Median time for surgical resection was 6 weeks.

RESULTS

Median follow-up for the group was 28 months (range 5-57 months). Six patients were felt to be persistently unresectable or developed distant metastases and did not undergo surgical resection. Of the 29 patients, 23 proceeded to surgery, 18 were resectable for cure, 13 by abdominoperineal resection, 3 by anterior resection and 2 by local excision. Of the 29 patients, 4 (13%) had a complete response, and 90% were clinically downstaged. Of the 18 resected patients, 1 has died of his disease, 17 are alive, and 15 disease-free. The regimen was well tolerated; there was only one treatment-related complication, a wound dehiscence.

CONCLUSION

The combination of 5 FU infusion and pelvic radiation in the management of locally advanced rectal cancer is well tolerated and provides a baseline for comparison purposes with future combinations of newer systemic agents and radiation.

Hypercalcemia and carcinoma of the penis

Hypercalcemia is the most common metabolic disorder associated with malignancies. Squamous cell carcinoma of the penis is a tumor for which this abnormality has rarely been described. This report presents a case of hypercalcemia seen in a patient with advanced penile cancer. A chemotherapy regimen of intravenous cisplatin and fluorouracil caused regression of the primary tumor and normalization of the serum calcium. A literature review supported an association between squamous cell carcinoma of the penis and hypercalcemia.

A case of melanoma concurrent with progressive systemic sclerosis

The association between progressive systemic sclerosis (PSS; scleroderma) and malignancy has been a controversial issue in the literature. The present report describes a rare case of concurrent malignant melanoma and PSS. A literature review suggests a possible connection between these two conditions.

Sensitivity of BB rat beta cells as determined by dose-responses to the cytotoxic effects of streptozotocin and alloxan

BB rats of diabetes-prone lines develop a spontaneous Type 1 diabetic syndrome, with many immunological concomitants. No data are available as to the integrity of their islet beta cells prior to onset of the insulitis which proceeds to their selective destruction. We tested the effects of the beta-cytotoxins streptozotocin and alloxan on such rats, compared to Wistar and to non diabetes-prone BB control rats studied prior to usual age of diabetes onset. A dose-response of a single injection of the agents with respect to pancreatic insulin content 48 hr post-injection as well as to circulating insulin and glucose, weight, and lymphocyte counts was established. Clear dose-responses were found for pancreatic insulin content. Though less sensitive, plasma insulin and glucose values showed responses. Whereas some litters of diabetes-prone rats showed greater reductions of pancreatic insulin than controls after some doses of streptozotocin, overall results in 8-26 recipients of each dose showed no significant differences when compared with either BB or Wistar controls. With smaller numbers of diabetes-prone rats, the same was obtained for alloxan, though with fewer doses tested. The latter required the construction of an alloxan dose-response in normal Wistar rats. Thus, this study has not demonstrated a nonspecific increase in "fragility" of BB rat beta cells in response to these classical diabetogenic agents. This would be consistent with other data suggesting that the primary abnormality in the syndrome does not necessarily reside within the beta cell.