Quality of Life Implications of Dose-Escalated External Beam Radiation for Localized Prostate Cancer: Results of a Prospective Randomized Phase 3 Clinical Trial, NRG/RTOG 0126

PURPOSE

External beam radiation therapy (EBRT) dose escalation has been tested in multiple prospective trials. However, the impact on patient reported outcomes (PROs) associated with higher doses of EBRT remain poorly understood. We sought to assess the differences in PROs between men treated with a dose of 70.2 Gy versus 79.2 Gy of EBRT for prostate cancer.

METHODS AND MATERIALS

The phase 3 clinical trial RTOG 0126 randomized 1532 patients with prostate cancer between March 2002 and August 2008 to 79.2 Gy over 44 fractions versus 70.2 Gy over 39 fractions. Eligible patients participated in the PRO data collection. PROs completed included the International Index of Erectile Function Questionnaire (IIEF), Functional Alterations due to Changes in Elimination (FACE), and the Spitzer Quality of Life Index (SQLI). The timepoints for the IIEF were collected pre-entry and at 6, 12, and 24 months. The FACE and SQLI were collected pre-entry and at 3, 6, 12, 18, and 24 months. The impact of EBRT dose to normal structures (penile bulb, rectum, and bladder) on PROs was also examined. Mixed effects models were used to analyze trends across time.

RESULTS

In total, 1144 patients completed baseline IIEF forms and of these, 56%, 64%, and 61% completed the IIEF at 6, 12, and 24 months, respectively; 1123 patients completed the FACE score at baseline and 50%, 61%, 73%, 61%, and 65% completed all 15 items for the FACE metric at timepoints of 3, 6, 12, 18, and 24 months, respectively. Erectile dysfunction at 12 months based on the single question was not significantly different between arms (38.1% for the standard dose radiation therapy arm vs 49.7% for the dose escalated radiation therapy arm; P = .051). Treatment arm (70.2 vs 79.2) had no significant impact on any PRO metrics measured across all collected domains. Comprehensive dosimetric analyses are presented and reveal multiple significant differences to regional organs at risk.

CONCLUSIONS

Compliance with PRO data collection was lower than anticipated in this phase 3 trial. Examining the available data, dose escalated EBRT did not appear to be associated with any detriment to PROs across numerous prospectively collected domains. These data, notwithstanding limitations, add to our understanding of the implications of EBRT dose escalation in prostate cancer. Furthermore, these results illustrate challenges associated with PRO data collection.

Trophic transfer efficiency in the Lake Superior food web: assessing the impacts of non-native species

Ecosystem-based management relies on understanding how perturbations influence ecosystem structure and function (e.g., invasive species, exploitation, abiotic changes). However, data on unimpacted systems are scarce, therefore, we often rely on impacted systems to make inferences about 'natural states.' Among the Laurentian Great Lakes, Lake Superior provides a unique case study to address non-native species impacts because the food web is dominated by native species. Additionally, Lake Superior is both vertically (benthic versus pelagic) and horizontally (nearshore versus offshore) structured by depth, providing an opportunity to compare the function of these sub-food webs. We developed an updated Lake Superior EcoPath model using data from the 2005/2006 lake-wide multi-agency surveys covering multiple trophic levels. We then compared trophic transfer efficiency (TTE) to previously published EcoPath models. Finally, we compared ecosystem function of the 2005/2006 ecosystem to that with non-native linkages removed and compared native versus non-native species-specific approximations of TTE and trophic flow. Lake Superior was relatively efficient (TTE = 0.14) compared to systems reported in a global review (average TTE = 0.09) and the microbial loop was highly efficient (TTE > 0.20). Non-native species represented a very small proportion (<0.01%) of total biomass and were generally more efficient and had higher trophic flow compared to native species. Our results provide valuable insight into the importance of the microbial loop and represent a baseline estimate of non-native species impacts on Lake Superior. Finally, this work is a starting point for further model development to predict future changes in the Lake Superior ecosystem.

INNOVATE (NRG-GU008): A randomized phase III trial of salvage radiotherapy and androgen deprivation therapy (ADT) with/without abiraterone and apalutamide for patients with node-positive prostate cancer after radical prostatectomy

TPS179

Background: Node-positive prostate cancer comprises for approximately 13% of newly-diagnosed patients and represents an aggressive form of the disease, but has been historically understudied in therapeutic clinical trials. Cure rates remain suboptimal for these patients with early stage IV disease, so clinical trials to intensify systemic treatment are warranted. Abiraterone and apalutamide have each demonstrated efficacy in improving metastasis-free survival and/or overall survival in the advanced stage setting, including both castrate-resistant and metastatic castration-sensitive prostate cancer. The mechanisms of action of abiraterone and apalutamide are complementary, and combination therapy has been shown in a prior Phase Ib trial to be safe and well-tolerated. Methods: Patients with pathologic node-positive disease by radical prostatectomy and who subsequently have a detectable PSA are eligible for this randomized controlled trial. All patients are required to receive molecular imaging (FACBC, PSMA, or choline PET scan) at trial entry and must have no radiographic evidence of distant metastasis in order to remain eligible. Eligible patients are randomized 1:1 to (control arm) salvage radiation therapy with 2 years of ADT vs (experimental arm) addition of 2 years of abiraterone/prednisone and apalutamide. The primary endpoint is metastasis-free survival. With a sample size of 586 and with a potential for 10% loss to follow-up, the trial has 90% power with one-sided alpha=0.025 to detect a HR of 0.53 for the experimental arm vs control arm for the primary endpoint. Secondary endpoints include quality of life (EPIC-26, EQ5D-5L, Brief Pain Inventory, PROMIS-Fatigue), overall survival, time to castrate resistance, and other disease-related outcomes. In addition, data will be collected to validate the Decipher score and PAM50-based classification as predictive biomarkers in this node-positive patient population. Trial was activated on March 5, 2020, and is currently enrolling patients. This project was supported by grants U10CA180868 (NRG Oncology Operations), U10CA180822 (NRG Oncology SDMC), U24CA196067 (NRG Oncology Specimen Bank) from the National Cancer Institute (NCI) and Janssen and GenomeDX. Clinical trial information: NCT04134260.

Randomized phase III trial to evaluate radiopharmaceuticals and zoledronic acid in the palliation of osteoblastic metastases from lung, breast, and prostate cancer: report of the NRG Oncology RTOG 0517 trial

BACKGROUND

Skeletal-related events (SREs), common sequelae of metastatic cancer, are reduced by bisphosphonates. In this study, it was postulated that radiopharmaceuticals, added to bisphosphonates, could further decrease the incidence of SREs.

METHODS

NRG Oncology RTOG 0517 randomized patients with breast, lung, and prostate cancer and blastic bone metastases to either zoledronic acid (ZA) alone or ZA plus radiopharmaceuticals (Sr-89 or Sm-153). The primary endpoint was time to development of SREs. Secondary objectives included quality of life (QOL), pain control, overall survival (OS), and toxicity.

RESULTS

261 patients (median age 68; 62% male; 55% prostate, 35% breast, 10% lung) were accrued between July 2006 and February 2011. The study closed early due to a lower than expected rate of SREs. 52 (42%) patients in the ZA arm and 49 (40%) in the radiopharmaceutical arm experienced an SRE. Median time free of SREs was 29.9 and 27.4 months, respectively (p = 0.84). Median OS in the ZA arm and radiopharmaceutical arms was 32.1 and 26.9 months, respectively (p = 0.37). Cox proportional hazards regression model showed that primary disease site (lung) and number of bone metastases (> 2) had a negative impact on OS (p < 0.0001, p = 0.01, respectively). The addition of radiopharmaceuticals to ZA led to a significant reduction in pain at 1 month based on BPI worst score (p = 0.02). No other group differences were noted for QOL or toxicity.

CONCLUSION

The addition of radiopharmaceuticals to bisphosphonates did not alter time to SREs or OS for patients with breast, lung, prostate cancers and blastic bone metastases, although it was associated with significant pain reduction at 1 month.

CLINICAL TRIAL REGISTRY

This protocol (RTOG 0517) is registered with ClinicalTrials.gov (NCT00365105), and may be viewed online at http://www.clinicaltrials.gov/ct2/show/NCT00365105?term=RTOG+0517&rank=1 .

Quantifying Unnecessary Normal Tissue Complication Risks due to Suboptimal Planning: A Secondary Study of RTOG 0126

PURPOSE

The purpose of this study was to quantify the frequency and clinical severity of quality deficiencies in intensity modulated radiation therapy (IMRT) planning in the Radiation Therapy Oncology Group 0126 protocol.

METHODS AND MATERIALS

A total of 219 IMRT patients from the high-dose arm (79.2 Gy) of RTOG 0126 were analyzed. To quantify plan quality, we used established knowledge-based methods for patient-specific dose-volume histogram (DVH) prediction of organs at risk and a Lyman-Kutcher-Burman (LKB) model for grade ≥2 rectal complications to convert DVHs into normal tissue complication probabilities (NTCPs). The LKB model was validated by fitting dose-response parameters relative to observed toxicities. The 90th percentile (22 of 219) of plans with the lowest excess risk (difference between clinical and model-predicted NTCP) were used to create a model for the presumed best practices in the protocol (pDVH0126,top10%). Applying the resultant model to the entire sample enabled comparisons between DVHs that patients could have received to DVHs they actually received. Excess risk quantified the clinical impact of suboptimal planning. Accuracy of pDVH predictions was validated by replanning 30 of 219 patients (13.7%), including equal numbers of presumed "high-quality," "low-quality," and randomly sampled plans. NTCP-predicted toxicities were compared to adverse events on protocol.

RESULTS

Existing models showed that bladder-sparing variations were less prevalent than rectum quality variations and that increased rectal sparing was not correlated with target metrics (dose received by 98% and 2% of the PTV, respectively). Observed toxicities were consistent with current LKB parameters. Converting DVH and pDVH0126,top10% to rectal NTCPs, we observed 94 of 219 patients (42.9%) with ≥5% excess risk, 20 of 219 patients (9.1%) with ≥10% excess risk, and 2 of 219 patients (0.9%) with ≥15% excess risk. Replanning demonstrated the predicted NTCP reductions while maintaining the volume of the PTV receiving prescription dose. An equivalent sample of high-quality plans showed fewer toxicities than low-quality plans, 6 of 73 versus 10 of 73 respectively, although these differences were not significant (P=.21) due to insufficient statistical power in this retrospective study.

CONCLUSIONS

Plan quality deficiencies in RTOG 0126 exposed patients to substantial excess risk for rectal complications.

A randomized trial of 79.2Gy versus 70.2Gy radiation therapy (RT) for localized prostate cancer

4

Background: RTOG 0126 is a phase III trial for localized prostate cancer (PC) testing whether dose escalation to 79.2Gy with 3DCRT or IMRT will improve overall survival (OS). Methods: Stage cT1b-T2b with Gleason Score (GS) 2-6 and PSA ≥ 10 and <20 or GS 7 and PSA <15 were eligible and randomized to receive 79.2Gy or 70.2Gy. No androgen withdrawal was used. Treatment was 3DCRT or IMRT to 79.2Gy in 44 fractions or 70.2Gy in 39 fractions. The objective was to detect a 23% reduction in mortality hazard (HR=0.77) for 79.2Gy. ASTRO and Phoenix definition was used for biochemical failure (BF). Time to local progression (LP), distant metastases (DM), PC death, and late GI/GU toxicity was calculated from date of registration. OS was estimated by Kaplan Meier and arms compared with log rank test. BF, LP, DM, time to late GI/GU, and PC death were estimated by cumulative incidence method and arms compared with Gray’s test. Results: 1,532 men were randomized, 763 to 79.2Gy and 769 to 70.2Gy. 1,499 were eligible, 751 and 748 in the 79.2Gy and 70.2Gy arms respectively. Median age was 69, 70% had PSA < 10 ng/ml, 84% with GS 7, 57% had T1 disease, and 66% used 3D-CRT. With a median of 7.0 years follow up, the 5 and 10-yr rates of OS are 88% and 67% with 79.2Gy and 89% and 66% with 70.2Gy (p=0.87; HR (95%CI)=0.98 (0.79,1.21)). The ASTRO (Phoenix) BF rates at 5 and 10 yr are 25% (16%) and 30% (26%) with 79.2Gy and 40% (21%) and 45% (43%) with 70.2Gy (both p<0.0001). The 5 and 10-yr rates of LP are 1% and 4% with 79.2Gy and 2% and 8% with 70.2Gy (p=0.0059; HR (95%CI)=0.46 (0.27,0.81)). The 5 and 10 yr rates of DM are 2% and 5% with 79.2Gy and 3% and 8% with 70.2Gy (p=0.026; HR (95%CI)=0.57 (0.35,0.94)). The high dose arm had lower rate of salvage therapy, 13.5% vs 21%, p=0.0002. The 10 yr rates for time to late grade ≥ 2 GI/GU are 22%/15% with 79.2Gy and 16%/10% with 70.2Gy (p=0.0063/p=0.001). Time to late grade ≥ 3 GI was higher for the 79.2Gy arm (p=0.035) but time to late grade ≥ 3 GU toxicity was not (p=0.14). Conclusions: Despite significant improvement in BF, DM, and LP rates, dose escalation did not improve OS. Patients receiving high dose radiation experience more late toxicity. Clinical trial information: NCT00033631.

Duration of androgen suppression before radiotherapy for localized prostate cancer: radiation therapy oncology group randomized clinical trial 9910

PURPOSE

To determine whether prolonged androgen suppression (AS) duration before radiotherapy improves survival and disease control in prostate cancer.

PATIENTS AND METHODS

One thousand five hundred seventy-nine men with intermediate-risk prostate cancer were randomly assigned to 8 weeks of AS followed by radiotherapy with an additional 8 weeks of concurrent AS (16 weeks total) or to 28 weeks of AS followed by radiotherapy with an additional 8 weeks of AS (36 weeks total). The trial sought primarily to detect a 33% reduction in the hazard of prostate cancer death in the 28-week assignment. Time-to-event end points are reported for up to 10 years of follow-up.

RESULTS

There were no between-group differences in baseline characteristics of 1,489 eligible patients with follow-up. For the 8- and 28-week assignments, 10-year disease-specific survival rates were 95% (95% CI, 93.3% to 97.0%) and 96% (95% CI, 94.6% to 98.0%; hazard ratio [HR], 0.81; P = .45), respectively, and 10-year overall survival rates were 66% (95% CI, 62.0% to 69.9%) and 67% (95% CI, 63.0% to 70.8%; HR, 0.95; P = .62), respectively. For the 8- and 28-week assignments, 10-year cumulative incidences of locoregional progression were 6% (95% CI, 4.3% to 8.0%) and 4% (95% CI, 2.5% to 5.7%; HR, 0.65; P = .07), respectively; 10-year distant metastasis cumulative incidences were 6% (95% CI, 4.0% to 7.7%) and 6% (95% CI, 4.0% to 7.6%; HR, 1.07; P = .80), respectively; and 10-year prostate-specific antigen-based recurrence cumulative incidences were 27% (95% CI, 23.1% to 29.8%) and 27% (95% CI, 23.4% to 30.3%; HR, 0.97; P = .77), respectively.

CONCLUSION

Extending AS duration from 8 weeks to 28 weeks before radiotherapy did not improve outcomes. A lower than expected prostate cancer death rate reduced ability to detect a between-group difference in disease-specific survival. The schedule of 8 weeks of AS before radiotherapy plus 8 weeks of AS during radiotherapy remains a standard of care in intermediate-risk prostate cancer.

Prostate-specific antigen response after short-term hormone therapy plus external-beam radiotherapy and outcome in patients treated on Radiation Therapy Oncology Group study 9413

BACKGROUND

The objective of this study was to assess the impact of a prostate-specific antigen (PSA) complete response (PSA-CR), measured at the end of external-beam radiotherapy and short-term hormone therapy, on treatment outcomes.

METHODS

The phase 3 Radiation Therapy Oncology Group 9413 trial, as part of its original protocol, used the assessment of PSA-CR (ie, PSA ≤0.3 ng/mL) at the end of short-term HT as a secondary endpoint. Short-term HT consisted of futamide plus a lutenizing hormone-releasing hormone agonist for 4 months. The Kaplan-Meier method was used to estimate overall survival (OS) and disease-free survival. Cumulative incidence was used to estimate biochemical failure, distant metastasis, and disease-specific survival. Univariate and multivariate analyses were performed to correlate PSA-CR after short-term hormone therapy with all endpoints, and the following variables were considered for analysis: PSA at baseline, Gleason score, treatment arm, age, and baseline testosterone status. Phoenix consensus definition was used to define PSA failure.

RESULTS

For 1070 evaluable patients, the median PSA at the end of short-term hormone therapy was 0.2 ng/mL. In total, 744 patients (70%) had a PSA-CR. At a median follow-up of 7.2 years, failure to obtain a PSA-CR was associated significantly with worse disease-specific survival (P = .0003; hazard ratio [HR], 2.03; 95% confidence interval [CI], 1.38-2.97), with worse disease-free survival (P = .003; HR, 1.28; 95% CI, 1.09-1.50), and with a higher incidence of distant metastasis (P = .0002; HR, 1.92; 95% CI, 1.37-2.69) and biochemical failure (P < .0001; HR, 1.57; 95% CI, 1.29-1.91). Other factors that were associated with worse disease-specific survival were Gleason scores from 8 to 10 (P = .0002; HR, 3.06; 95% CI, 1.71-5.47) and PSA levels >20 ng/mL (P = .04; HR, 1.55; 95% CI, 1.02-2.30).

CONCLUSIONS

The current results indicated that failure to obtain a PSA-CR (PSA ≤0.3 ng/mL) after short-term hormone therapy and external-beam radiotherapy appears to be an independent predictor of unfavorable outcomes and could help identify patients who may benefit from the addition of long-term androgen ablation.

Randomized phase III trial to evaluate radiopharmaceuticals and zoledronic acid in the palliation of osteoblastic metastases from lung, breast, and prostate cancer: Report of RTOG 0517

TPS9150

Background: Skeletal related events (SREs) diminish quality of life (QOL) as well as overall survival (OS) in patients with bone metastases, a common event in breast, lung and prostate cancer. SREs can be reduced or delayed by the use of bisphosphonates. It is postulated that the radiopharmaceuticals, Strontium-89 (Sr89) and Samarium-153 (Sm153), when added to a bisphosphonate can decrease the incidence of SREs. Methods: RTOG 0517 randomized patients with breast, lung and prostate cancer and blastic bone metastases to either Zoledronic acid (ZA) alone or ZA plus a single standard dose of either Sr89 or Sm153. No limitations were placed on additional therapy such as chemotherapy or hormonal treatment. The projected median time to SRE [pathological bone fracture, spinal cord compression, surgery to bone, or radiation to bone] for the ZA arm was 10.4 months requiring 257 SRE events to detect a 33% relative reduction for the radiopharmaceutical arm in the time to development of an SRE with 90% power. Other study objectives included quality of life, pain control, OS and toxicity. Results: 261 patients (median age 68; 62% male; 55% prostate, 35% breast, 10% lung) were accrued from July 2006 through February 2011 (4.6 patients/month). Due to a lower than expected rate of SREs in the control (ZA) arm, the study was closed early and therefore did not reach the targeted accrual. 28 (17.4%) patients in the ZA arm and 27 (16.8%) in the radiopharmaceutical arm experienced an SRE. Median time to development of an SRE in the ZA and radiopharmaceutical arms was 11.60 and 16.74 months, respectively (p=.47). Median OS in the ZA arm and radiopharmaceutical arm was 15.95 and 11.18 months, respectively (p=0.12). Cox proportional hazards regression model showed that baseline characteristics, including gender, race, ethnicity, primary disease site or number of bone metastases, had no significant impact on OS. There was no difference in QOL parameters or toxicities between the two arms. Conclusion: Patients receiving ZA only experienced a much lower SRE rate than was hypothesized. The addition of Sr89 or Sm153 did not result in a difference in SREs, OS, or QOL

Development of RTOG consensus guidelines for the definition of the clinical target volume for postoperative conformal radiation therapy for prostate cancer

PURPOSE

To define a prostate fossa clinical target volume (PF-CTV) for Radiation Therapy Oncology Group (RTOG) trials using postoperative radiotherapy for prostate cancer.

METHODS AND MATERIALS

An RTOG-sponsored meeting was held to define an appropriate PF-CTV after radical prostatectomy. Data were presented describing radiographic failure patterns after surgery. Target volumes used in previous trials were reviewed. Using contours independently submitted by 13 radiation oncologists, a statistical imputation method derived a preliminary "consensus" PF-CTV.

RESULTS

Starting from the model-derived CTV, consensus was reached for a CT image-based PF-CTV. The PF-CTV should extend superiorly from the level of the caudal vas deferens remnant to >8-12 mm inferior to vesicourethral anastomosis (VUA). Below the superior border of the pubic symphysis, the anterior border extends to the posterior aspect of the pubis and posteriorly to the rectum, where it may be concave at the level of the VUA. At this level, the lateral border extends to the levator ani. Above the pubic symphysis, the anterior border should encompass the posterior 1-2 cm of the bladder wall; posteriorly, it is bounded by the mesorectal fascia. At this level, the lateral border is the sacrorectogenitopubic fascia. Seminal vesicle remnants, if present, should be included in the CTV if there is pathologic evidence of their involvement.

CONCLUSIONS

Consensus on postoperative PF-CTV for RT after prostatectomy was reached and is available as a CT image atlas on the RTOG website. This will allow uniformity in defining PF-CTV for clinical trials that include postprostatectomy RT.

Phase III trial comparing whole-pelvic versus prostate-only radiotherapy and neoadjuvant versus adjuvant combined androgen suppression: Radiation Therapy Oncology Group 9413

PURPOSE

This trial tested the hypothesis that combined androgen suppression (CAS) and whole-pelvic (WP) radiotherapy (RT) followed by a boost to the prostate improves progression-free survival (PFS) by 10% compared with CAS and prostate-only (PO) RT. This trial also tested the hypothesis that neoadjuvant and concurrent hormonal therapy (NCHT) improves PFS compared with adjuvant hormonal therapy (AHT) by 10%.

MATERIALS AND METHODS

Eligibility included localized prostate cancer with an elevated prostate-specific antigen (PSA) < or = 100 ng/mL and an estimated risk of lymph node (LN) involvement of 15%. Between April 1, 1995, and June 1, 1999, 1,323 patients were accrued. Patients were randomly assigned to WP + NCHT, PO + NCHT, WP + AHT, or PO + AHT. Failure for PFS was defined as the first occurrence of local, regional, or distant disease; PSA failure; or death for any cause.

RESULTS

With a median follow-up of 59.5 months, WP RT was associated with a 4-year PFS of 54% compared with 47% in patients treated with PO RT (P =.022). Patients treated with NCHT experienced a 4-year PFS of 52% versus 49% for AHT (P =.56). When comparing all four arms, there was a progression-free difference among WP RT + NCHT, PO RT + NCHT, WP RT + AHT, and PO RT + AHT (60% v 44% v 49% v 50%, respectively; P =.008). No survival advantage has yet been seen.

CONCLUSION

WP RT + NCHT improves PFS compared with PO RT and NCHT or PO RT and AHT, and compared with WP RT + AHT in patients with a risk of LN involvement of 15%.

Plasma cell granuloma of the nasal cavity treated by radiation therapy

Plasma cell granuloma is a rare, benign tumor most commonly found in the lungs in patients younger than 30 years. Although presentation has been reported at a number of other anatomic sites, this report is the first of plasma cell granuloma of the nasal cavity. The tumor was initially resected, but progression was seen at 1-month follow-up. Because further surgery to completely eradicate the tumor would have been extensive and disfiguring, 40-Gy external beam radiation was given in 20 fractions using a three-field wedge technique. Most recent clinical follow-up at 27 months showed local control. Surgery remains the treatment of choice for plasma cell granuloma when the disease can be completely resected. However, irradiation can also be effective in patients with recurrent or inoperable local disease.

Safety of adjunctive transvaginal beam therapy in the treatment of squamous cell carcinoma of the uterine cervix

At The University of Texas M. D. Anderson Hospital and Tumor Institute at Houston between 1970 and 1980, 159 patients with bulky cervical cancers of FIGO Stages IB or II were treated with transvaginal orthovoltage radiotherapy (TVR) as an adjunct to standard external beam megavoltage irradiation and brachytherapy. The majority received 10 or 15 Gy air dose in 2-3 fractions using 125-250 kVp X rays. The dose from TVR was ignored in subsequent standard treatment planning. The absolute 5-year local control and survival rates were 82 and 83%, respectively. A total of 9 patients (5.7%) developed serious treatment complications that were significantly related to performance of a staging lymphadenectomy prior to radiotherapy and to an external beam pelvic dose of 50 +/- 0.5 Gy versus 40 +/- 0.5 Gy. The risk complications was not related to the dose of TVR or brachytherapy within the ranges used. Provided patients are properly selected and appropriate technical precautions are exercised, TVR is a safe technique. It is effective in controlling bleeding and shrinking large exophytic tumors, and very likely contributes to improved tumor control by facilitating optimal geometry for intracavitary therapy.

Giant cell tumors of bone: treatment with radiation therapy

Records of 15 patients with giant cell tumor of bone treated with radiation therapy over a 35-year period were reviewed; ten patients for whom follow-up information was available constituted the study group. One patient was treated by means of orthovoltage equipment only, a second, by both orthovoltage and megavoltage equipment (cobalt 60). The remaining eight were all treated with megavoltage to doses of 40-52 Gy in 24-30 fractions. Seven patients are alive without disease, with an average survival of 192 months (range, 48-360 months). Three patients died of uncontrolled local and distant disease (average survival, 52 months; range, 23-99 months): one with metastasis in the lungs at time of treatment and two after treatment. Although incidence of lung metastasis appears high, it may be due to patient selection because chemotherapy had failed in all three. Complications from irradiation in one surviving patient required surgical closure of a dural fistula 19 years after treatment. No radiation-induced sarcomatous transformations of controlled tumors were noted. These data suggest that giant cell tumor of bone can be well controlled by radiation therapy. Megavoltage irradiation should be considered in treating local disease not easily controlled by surgery in the axial skeleton. Complications are minimal, and normal function can be preserved in the treated areas.

Insulin resistance for glucose metabolism in disused soleus muscle of mice

Our hypothesis was that insulin resistance for carbohydrate metabolism develops after a single day of muscular disuse. The immobilization of the mouse hindlimb for 24 h was used to produce muscular disuse (group c). As food intake was voluntarily decreased during the immobilization, two additional groups were used: group A was untreated and ate ad libitum, whereas group B was anesthetized with group C and was fed amounts of food similar to those eaten by group C. Because groups B and C differed only by limb immobilization, group B was used as the reference group. When insulin was present in the incubation media, the rates of 2-deoxyglucose uptake and glycogen synthesis were always significantly decreased in soleus muscles from group C (anesthetized, ate less, immobilized) as compared to group B (anesthetized, pair-fed food that group C ate). Significant interaction between the factors of insulin and muscular disuse for the rates of 2-deoxyglucose uptake and glycogen synthesis support the concept that disuse of skeletal muscle attenuates insulin action. These observations are a direct demonstration of a decrease in insulin responsiveness in skeletal muscle as the result of a single day of muscular inactivity. Because plasma insulin concentrations were significantly lower in groups B and C than in the untreated group, it seems likely that the development of insulin resistance in disused skeletal muscle is independent of plasma insulin levels.

Protein synthesis rates in atrophied gastrocnemius muscles after limb immobilization

Fractional rates of protein synthesis in rats were determined by the constant-infusion technique. Rates of protein synthesis in the gastrocnemius muscle were significantly reduced from control values throughout a 7-day period of hindlimb immobilization and 1) significantly increased to control values during the first 6 h following the 7-day period of hindlimb immobilization; 2) remained at control values for the next 2 days; and 3) then significantly increased to about twice control values on the 4th day following immobilization. Exercise of sufficient duration and/or intensity affected a further increase in the protein synthesis rate during recovery from atrophy. For example, running on a motor-driven treadmill 1 h daily for 3 days after ending limb immobilization resulted in a significant increase in the fractional rate of protein synthesis in the gastrocnemius muscle on the 2nd day following immobilization. Also, weight lifting for 200 s on the 2nd day of protein synthesis in the gastrocnemius muscle. Thus increased usage of atrophied muscle was followed by an increased rate of protein synthesis.

Longevity of exercising obese hypertensive rats

The purpose of this study was to determine whether daily running lengthens the life-span of animals dying prematurely due to cardiovascular disease. We used a strain of rat that is genetically hypertensive and obese and is reported to develop atherosclerosis (Exp. Mol. Pathol. 19: 53--60, 1973). These animals were divided into three groups consisting of runners exercised daily on treadmills from an early age life, food-restricted sedentary rats, and libitum eaters that were sedentary. This latter group had significantly higher average daily food intakes and body weights than either of the other two groups. The average life-span of both sedentary groups was significantly longer than the running group. Runners had a greater frequency of focal myocardial necrosis, but atherosclerosis was absent in all three groups. We speculate that daily running may have accentuated the development of factor s that may have contributed to the early death of runners.

The effects of cutting or of stretching skeletal muscle in vitro on the rates of protein synthesis and degradation

Rates of protein synthesis were significantly lower in the cut soleus and extensor digitorum longus muscles than in their uncut counterparts. Rates of protein degradation were significantly higher in cut soleus muscles, but not in cut extensor digitorum longus muscles as compared with their uncut controls. Concentrations of ATP and phosphocreatine were significantly lower in cut soleus and extensor digitorum longus muscles after incubation in vitro in contrast with respective control uncut muscles. These data indicate that cutting of muscle fibres alters rates of protein synthesis and degradation, in addition to altering concentrations of high-energy phosphates. Since these findings stressed the importance of using intact muscles to study protein metabolism, additional studies were made on intact muscles in vitro. Stretched soleus muscles had higher concentrations of high-energy phosphates at the end of an incubation period than did unstretched muscles. However, the length of the soleus, extensor digitorum longus and diaphragm muscles during incubation did not affect rates of protein degradation.U

Early change in skeletal muscle protein synthesis after limb immobilization of rats

The atrophy of skeletal muscle accruing from disuse, or limb immobilization, is caused by a decreased rate of protein synthesis and an increased rate of protein degradation. Currently, little information is available regarding the initial time of the decline in the rate of protein synthesis in skeletal muscle. The purpose of the present study was to determine, as precisely as possible, the time at which the protein synthesis rate first begins to decline in skeletal muscle, utilizing immobilized limbs of rats for a model. A constant-infusion technique employing [14C]tyrosine was used to estimate protein synthesis rates. During the first 6 h of immobilization, a significant decline of 37% in the fractional rate of protein synthesis from the control level of 5.7%/day was observed. These results suggest that very early changes are occurring in molecular events that regulate protein synthesis in disused or immobilized skeletal muscle.

Recovery of skeletal muscle after 3 mo of hindlimb immobilization in rats

During immobilization, skeletal muscle undergoes decreases in size and strength with concomitant atrophic and degenerative changes in slow-twitch muscle fibers. Currently there are no objective data in slow-twitch muscle demonstrating recovery of biochemical or physiological indices following termination of immobilization. The purpose of this study was to determine whether the soleus, a slow-twitch muscle, could recover normal biochemical or physiological levels following termination of immobliization. Adenosine triphosphate, glycogen, and protein concentration (mg/g wet wt) all significantly decreased following 90 days of hindlimb immobilization, but these three values returned to control levels by the 60th recovery day. Similarly, soleus muscle wet weight and protein content (mg protein/muscle) returned to control levels by the 14th recovery day. In contrast, maximal isometric tension did not return to normal until the 120th day. These results indicate that following muscular atrophy, which was achieved through 90 days of hindlimb immoblization, several biochemical and physiological values in skeletal muscle are recovered at various times after the end of immobilization.

Cow red blood cells. II. Stimulation of bovine red cell glycolysis by plasma

Cow red cell glycolysis, which can be stimulated by a variety of purines and pyrimidines, was also found to be elevated by its own plasma. Dialyzed or charcoal-treated plasma could no longer stimulate glycolysis, suggesting that the stimulating factors may be purines or pyrimidines. Determination of purines or pyrimidines in plasma revealed the presence of xanthine (0.31 muM), hypoxanthine (0.60 muM), and adenosine (0.05 muM), as well as unknown compounds. A physiologic level of hypoxanthine, with or without xanthine and adenosine approximating their concentrations in plasma, resulted in the stimulation of cow red cell glycolytic rate by 16% (P less than 0.01). These findings suggest that plasma-borne purines may act on cow red cells in concert with as yet unidentified factors. Moreover, exchanging calf and cow plasmas produced no stimulatory effect on either calf or cow red cell glycolysis, suggesting that a) calf red cells lack some of the cellular components that respond to this stimulator and, b) only cow plasma contains this specific stimulator. In other species, including dog, cat, rabbit, rat, guinea pig, and human, stimulation of glycolysis by plasma was not observed.

Cow red blood cells. I. Effect of purines, pyrimidines, and nucleosides in bovine red cell glycolysis

Cow red cells, under in vitro incubation conditions, exhibit a comparatively low glycolytic rate of 0.56 +/- 0.05 micromol/(ml cells.h), with a ratio of lactate formed to glucose consumed of 1.58. It has been found that this low glycolytic rate can be stimulated 50--60% above the basal level in the presence of a variety of purine and pyrimidine compounds including adenosine, inosine, adenine, hypoxanthine, xanthine, and uracil. In contrast, calf red cells, which have a much higher glycolytic rate, display no discernible response to these agents. In attempts to elucidate the mechanism by which this stimulation takes place, both glucose transport and glycolytic enzyme activities were determined in the presence of these stimulators. Glucose influx in cow red cells, measured using the glucose analog 3-O-methyl-glucose, exhibits both a low Km of 117 microM and a Vmax of 0.38 micromol/(ml cells.min), and is unaltered in the presence of adenosine. On the other hand, hexokinase, which in normal hemolysates of cow red cells has an activity of 0.49 +/- 0.03 micromol/(g Hb.min). was found to be stimulated to 0.73 micromol/(g Hb.min) in the presence of adenine. Both pyruvate kinase and phosphofructokinase were unaffected by this compound. These data suggest that certain purines and pyrimidine compounds may exert their stimulatory effect on hexokinase activity, resulting in an augmentation of cow red cell glycolysis.