Trends and Outcomes of Proton Radiation Therapy Use for Non-Small Cell Lung Cancer

Purpose:

To examine national care patterns in proton radiation therapy (PBT) use for non–small cell lung cancer (NSCLC) and the effect of facility type on survival.

Patients and Methods:

Using the National Cancer Database, we identified 506 patients with a diagnosis of NSCLC from 2004-2014 who underwent PBT. Patients were categorized as having received treatment at an academic/research facility (ARF) or a form of community cancer program (CCP). Descriptive analysis was performed, and overall survival was analyzed by Kaplan-Meier methods and Cox proportional hazard models.

Results:

Treatments at ARFs and CCPs were equally distributed with 253 patients at each facility type. A positive trend in PBT use over time was observed with 2.8% of cases being treated in 2008 compared to 21.5% in 2014 (P = .001). Definitive doses (≥60 Gy) were more commonly given at ARFs than CCPs (72% versus 45%, respectively; P < .001). Five-year overall survival was 31% at ARFs and 18% at CCPs (P < .001). On multivariate analysis, outcomes were worse with treatments at CCPs (hazard ratio [HR] 1.61; 95% Confidence Interval, 1.14-2.27; P = .007). On subanalysis of nonsurgical patients treated with ≥60 Gy, facility type became insignificant and dose escalation was associated with improved outcomes (≥70 Gy HR 0.45; 95% CI, 0.25-0.81; P = .008).

Conclusion:

Use of PBT for management of NSCLC is on the rise. Community cancer programs were associated with higher rates of nondefinitive PBT doses and correspondingly worse outcomes. Differences in survival by facility became insignificant when definitive doses were used, warranting further investigation of practice patterns in CCPs at a national level.

Multimodal Imaging of Pathologic Response to Chemoradiation in Esophageal Cancer

PURPOSE

To examine the value of early changes in quantitative diffusion-weighted imaging and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for discriminating complete pathologic response (pCR) to chemoradiation in esophageal cancer.

METHODS AND MATERIALS

Twenty esophageal cancer patients treated with chemoradiation followed by surgery were prospectively enrolled. Patients underwent magnetic resonance imaging and FDG-PET/CT scans at baseline, interim (2 weeks after chemoradiation start), and first follow-up. On the basis of pathologic findings at surgery, patients were categorized into tumor regression groups (TRG1, TRG2, and TRG3+). Distributions of summary statistics in apparent diffusion coefficient (ADC) and FDG-PET at baseline and relative changes at interim and follow-up scans were compared between pCR/TRG1 and non-pCR/TRG2+ groups and across readers. Receiver operating characteristics were evaluated for summary measures to characterize discrimination of pCR from non-pCR.

RESULTS

Relative changes in tumor volume ADC (ΔADC) mean and 25th and 10th percentiles from baseline to interim were able to completely discriminate (area under the curve = 1, P < .0011) between pCR and non-pCR (thresholds = 27.7%, 29.2%, and 32.1%, respectively) and were found to have high interreader reliability (95% limits of agreement of 1.001, 0.944, and 0.940, respectively). Relative change in total lesion glycolysis (TLG) from baseline to interim was significantly different among pCR and non-pCR groups (P=.0117) and yielded an area under the curve of 0.947 (95% confidence interval 0.8505-1.043). An optimal threshold of 59% decrease in TLG provided optimal sensitivity (specificity) of 1.000 (0.867). Changes in ADC summary measures were negatively correlated with that of TLG (Spearman, -0.495, P=.027).

CONCLUSIONS

Quantitative volume ΔADC and TLG during treatment may serve as early imaging biomarkers for discriminating pathologic response to chemoradiation in esophageal cancer. Validation of these data in larger, prospective, multicenter studies is essential.

Practice patterns and outcomes of chemoradiotherapy versus radiotherapy alone for older patients with nasopharyngeal cancer

Older patients are at increased risk of toxicities from aggressive oncologic therapy and of nononcologic death. A meta‐analysis of non‐nasopharyngeal head and neck cancers showed no statistical benefit in adding chemotherapy to radiotherapy (RT) in older patients; another meta‐analysis of RT versus chemoradiotherapy (CRT) in NPC found advantages to CRT, but vastly under‐represented patients ≥70 years old. This is the largest study to date evaluating outcomes of CRT versus RT alone in this population. The National Cancer Data Base (NCDB) was queried for primary nasopharyngeal cancer cases (2004–2013) in patients ≥70 years old receiving RT alone or CRT. Patients with unknown RT/chemotherapy and T1N0 or M1 disease were excluded. Logistic regression analysis ascertained factors associated with CRT delivery. Kaplan–Meier analysis evaluated overall survival (OS) between both cohorts. Cox proportional hazards modeling determined variables associated with OS. In total, 930 patients were analyzed (n = 713 (77%) CRT, n = 217 (23%) RT). Groups were relatively balanced; CRT was less frequently delivered in patients with advancing age, lower nodal burden, and females (P < 0.05 for all). Median OS in the CRT and RT groups were 35.3 versus 20.0 months, respectively (P = 0.002). On multivariate analysis, independent predictors of OS included age, comorbidities, income and insurance status, tumor grade, and stage (P < 0.05 for all). Notably, receipt of chemotherapy independently predicted for improved OS (P = 0.036). CRT, compared to RT alone, was independently associated with improved survival in NPC patients ≥70 years old. CRT appears to be a promising approach in this population, but treatment‐related toxicity risks should continue to be weighed against potential oncologic benefits.

Concurrent Versus Sequential Chemoradiation Therapy in Completely Resected Pathologic N2 Non-Small Cell Lung Cancer: Propensity-Matched Analysis of the National Cancer Data Base

BACKGROUND

Following complete resection of pN2 non-small cell lung cancer (NSCLC), national guidelines recommend either sequential (sCRT) or concurrent chemoradiotherapy (cCRT). This is the largest study to date evaluating survival between both approaches. In sCRT patients, sequencing 'chemotherapy first' versus 'radiotherapy first' was also addressed.

METHODS

The National Cancer Data Base (NCDB) was queried for patients with primary NSCLC undergoing surgery (without neoadjuvant radiotherapy or chemotherapy), pN2 disease with negative surgical margins, and receiving postoperative CRT. Multivariable logistic regression ascertained factors associated with cCRT administration. Kaplan-Meier analysis evaluated overall survival (OS), and Cox proportional hazards modeling determined variables associated with OS. Propensity matching was performed to address group imbalances and indication biases.

RESULTS

Of 1924 total patients, 1115 (58%) received sCRT and 809 (42%) underwent cCRT. Median OS in the sCRT and cCRT cohorts was 53 months versus 37 months (p < 0.001); differences persisted following propensity matching (p = 0.002). In the sCRT population, there was a trend for higher OS in the 'chemotherapy first' group, relative to 'radiotherapy first' (55 vs. 44 months, p = 0.079), but there were no statistically apparent differences following propensity matching (p = 0.302).

CONCLUSIONS

For completely resected pN2 NSCLC, delivering adjuvant sCRT was associated with improved survival over cCRT. Toxicity-related factors may help to explain these results but need to be better addressed in further investigations. Differential sequencing of sCRT did not appear to affect survival.

The optimal treatment approaches for stage I small cell lung cancer

Although small cell lung cancer (SCLC) represents less than one-sixth of all lung cancer cases, it is an aggressive disease with a high metastatic potential to various sites including the brain. Most landmark trials assessing individual therapy benefits for SCLC dichotomized patients as having either limited or extensive disease. Over the last decade, however, there has been a clear shift towards categorizing and analyzing survival patterns using a more thorough staging system that accounts for tumor size and the degree of nodal or metastatic disease burden. For the 5% of patients who present with clinical stage I (cT1-2aN0M0) SCLC, extrapolating treatment recommendations from a rather heterogeneous population that constitutes limited disease SCLC remains controversial and has led to numerous investigations of alternative therapies such as stereotactic body radiation therapy (SBRT) for the management of this highly select group of patients. Given the changing landscape of multimodal therapy, this review will summarize relevant data pertaining to and outline optimal treatment algorithms for stage I SCLC, with a particular focus on SBRT as a primary mode of local therapy.

Treatment disparities affect outcomes for patients with stage I esophageal cancer: a national cancer data base analysis

Background

To examine patterns of care and outcomes for patients with stage I esophageal cancer (EC) in the United States.

Methods

We identified patients in the National Cancer Data Base diagnosed with stage I EC from 2004 to 2012 and grouped them by primary treatment: esophagectomy (Eso), local excision (LE), concurrent chemoradiation (CRT), or observation (Obs). Multinomial logistic regression was used to predict receipt of treatments. Overall survival (OS) was estimated by Kaplan-Meier methods adjusted for inverse probability of treatment weighting (IPTW) and Cox proportional hazard regressions.

Results

Of 5,480 patients, 2,312 (42%) underwent Eso, 1,250 (23%) LE, 758 (14%) CRT, and 1,160 (21%) Obs. LE use increased over time from 17% to 29% while Obs declined from 26% to 19%. Patients least likely to undergo surgery were older, had greater comorbidity, were uninsured, were treated at non-academic centers, and were Black. The rate of surgery for Black patients was half of that for White patients (33% vs. 67%). Postoperative mortality rates were higher after Eso vs. LE at 30 days (2.9% vs. 0.5%; P<0.001) and at 90 days (5.5% vs. 1.4%, P<0.001). Five-year OS was 59% with Eso, 63% LE, 29% CRT, and 31% Obs (P<0.001). On multivariate analysis, outcomes were best after LE [vs. Eso: hazard ratio (HR) =1.15, 95% CI: 1.01-1.30, P=0.037; CRT: HR =2.41, 95% CI: 2.09-2.78, P<0.001; Obs: HR =3.79, 95% CI: 3.33-4.32, P<0.001).

Conclusions

Disparities are evident in the care of patients with stage I EC throughout the United States. LE was associated with favorable outcomes compared to Eso, CRT, and Obs.

Use of regional nodal irradiation and its association with survival for women with high-risk, early stage breast cancer: A National Cancer Database analysis

Purpose

The role of regional nodal irradiation (RNI) for patients with breast cancer remains controversial, particularly on the basis of nodal involvement. Using the National Cancer Database, we aimed to validate published data on whether expanding treatment fields from whole-breast irradiation (WBI) to encompass the regional nodes (WBI+RNI) affected overall survival (OS) for patients with node-positive (pN1-3) or high-risk node-negative (pN0) breast cancer treated with breast-conserving surgery and adjuvant chemotherapy.

Methods and materials

Women diagnosed with invasive breast cancer between 2004 and 2012 who met the selection criteria for the National Cancer Institute of Canada MA.20 trial were identified and stratified by receipt of RNI. Propensity score matching was used to compare 1:1 matched pairs of patients. Five-year OS was estimated using the Kaplan-Meier method. We used multivariate logistic regression to predict receipt of WBI+RNI and a multivariable Cox model to examine associations between patients' demographic, tumor, and treatment characteristics and OS using double robust estimation.

Results

Of 23,567 patients, 6,920 (29%) received WBI+RNI and 16,647 (71%) WBI. Median follow-up was 56 months. Use of WBI+RNI increased from 25.2% in 2004 to 32.2% in 2012 (P < .001). Patients receiving WBI+RNI more often had negative hormone-receptor status, ≥5 cm tumors and >1 involved node, and were not privately insured. For all patients, the 5-year OS rates were 90.8% with WBI+RNI versus 92.6% with WBI (P < .001). In the matched cohort (n = 10,922), the corresponding 5-year OS rates were 92% and 91.9% (P = .45), respectively. On multivariate analysis, WBI+RNI did not affect OS in the matched cohort (hazard ratio, 1.02; 95% confidence interval, 0.89-1.17, P = .76), regardless of pathologic nodal status.

Conclusions

In this large retrospective analysis, use of WBI+RNI did not affect 5-year OS rates for women with high-risk, early stage breast cancer undergoing breast-conserving surgery and adjuvant chemotherapy, regardless of nodal status, which confirms the findings of the MA.20 trial.

Patterns of Care and Treatment Outcomes of Elderly Patients with Stage I Esophageal Cancer: Analysis of the National Cancer Data Base

INTRODUCTION

This study analyzes practice patterns, treatment-related mortality, survival, and predictors thereof in elderly patients with early-stage esophageal cancer (EC).

METHODS

The National Cancer Data Base was queried for cT1-2 N0 EC in patients 80 years of age and older. Patients were divided into four treatment groups: observation (Obs), chemoradiotherapy (CRT), local excision (LE), and esophagectomy (Eso). Patient, tumor, and treatment parameters were extracted and compared. Analyses were performed on overall survival (OS) and postoperative 30- and 90-day mortality.

RESULTS

A total of 923 patients from 2004 to 2012 were analyzed. Of these, 43% underwent clinical Obs, 22% underwent CRT, 25% underwent LE, and 10% underwent Eso. Patients undergoing Obs were older, had more comorbidities, were treated at nonacademic centers, and lived 25 miles or less from the facility. Patients receiving an operation (Eso or LE) were more often younger, male, white, and in the top income quartile. The postoperative 30-day mortality rates in the LE and Eso groups were 1.3% and 9.6%, respectively (p < 0.001) and increased to 2.6% and 20.2% at 90 days, respectively (p < 0.001). The 5-year OS rate was 7% for Obs, 20% for CRT, 33% for LE, and 45% for Eso (p < 0.001). Multivariate analyses showed improved OS with any local definitive therapy: CRT (hazard ratio [HR] = 0.42, 95% confidence interval [CI]: 0.34-0.52, p < 0.001), LE (HR = 0.3, 95% CI: 0.24-0.38, p < 0.001), and Eso (HR = 0.32, 95% CI: 0.23-0.44, p < 0.001).

CONCLUSIONS

There are noteworthy demographic, socioeconomic, and regional disparities influencing management of elderly patients with stage I EC. Despite high rates of Obs, careful consideration of all local therapy options is warranted, given the improved outcomes with treatment.

Advances in Radiotherapy Management of Esophageal Cancer

Radiation therapy (RT) as part of multidisciplinary oncologic care has been marked by profound advancements over the past decades. As part of multimodality therapy for esophageal cancer (EC), a prime goal of RT is to minimize not only treatment toxicities, but also postoperative complications and hospitalizations. Herein, discussion commences with the historical approaches to treating EC, including seminal trials supporting multimodality therapy. Subsequently, the impact of RT techniques, including three-dimensional conformal RT, intensity-modulated RT, and proton beam therapy, is examined through available data. We further discuss existing data and the potential for further development in the future, with an appraisal of the future outlook of technological advancements of RT for EC.

Evaluating the fate of patients who undergo resections of very large, node-negative lung cancers using the National Cancer DataBase

OBJECTIVES

To determine whether there are differences in survival associated with different treatment modalities among patients with lymph node-negative, very large non-small-cell lung cancers (NSCLCs).

METHODS

The National Cancer DataBase was used to identify patients diagnosed with NSCLCs >7 cm (T3) without lymph node involvement (N0) or metastatic disease (M0) from 1999 to 2006. Surgical therapy included surgery alone, neoadjuvant chemoradiation therapy or chemotherapy, surgery followed by adjuvant chemoradiation therapy or chemotherapy and surgery followed by postoperative radiation therapy (PORT). The 5-year overall survival (OS) was estimated by the Kaplan-Meier method and comparisons were made using log-rank tests and Cox regression models.

RESULTS

Of the 2296 patients identified with cT3N0M0 disease, 45% underwent surgical therapy. The 5-year OS rate was 38%. Across the different treatment regimens, there was a significant difference in 5-year OS. Neither neoadjuvant chemoradiation therapy or chemotherapy nor adjuvant chemoradiation therapy was associated with improved 5-year OS. The use of adjuvant chemotherapy was associated with improved OS relative to surgery alone [hazard ratio (HR) 0.70; 95% confidence interval (CI) 0.54-0.91, P = 0.008]. PORT alone was associated with a detrimental effect on 5-year OS relative to surgery alone [HR 2.04; 95% CI 1.38-3.03, P < 0.001].

CONCLUSIONS

Large T3N0 NSCLCs appear to be optimally treated with surgical resection followed by adjuvant chemotherapy.

Treating locally advanced disease: an analysis of very large, hilar lymph node positive non-small cell lung cancer using the National Cancer Data Base

BACKGROUND

Very large, locally advanced non-small cell lung cancers (NSCLC) remain a therapeutic challenge. This retrospective study compares the effect of treatment modalities on survival of patients with large NSCLC with hilar lymph node involvement (T3>7 cmN1).

METHODS

The National Cancer Data Base was used to identify adult patients who were diagnosed with T3>7 cmN1 NSCLC from 1999 to 2005 (n=642). Nonsurgical treatments included chemoradiation, chemotherapy, radiation therapy, or no treatment, whereas primary surgical treatments included surgery, chemoradiation or chemotherapy prior to surgery, chemoradiation or chemotherapy after surgery, or postoperative radiotherapy. Five-year overall survival (OS) was estimated by the Kaplan-Meier method and comparisons made using log-rank tests and Cox regression models.

RESULTS

A total of 642 patients were evaluated; 425 nonsurgical (66%) and 217 surgical (34%). Primary surgical therapy was associated with improved 5-year OS; 28% versus 8% and 4% for nonsurgical and no treatment, respectively (p<0.001). The 5-year OS were 11%, 5%, 2%, and 4% for chemoradiation, chemotherapy, radiation therapy, and no treatment, respectively (p<0.001). The 5-year OS were 16% for surgery only, 40% and 44% for neoadjuvant chemoradiation or chemotherapy with surgery, respectively, 40% and 38% for adjuvant chemoradiation or chemotherapy with surgery, respectively, and 18% for postoperative radiotherapy (p<0.001). On multivariate analysis, surgery and chemotherapy in most combinations were associated with significantly improved OS compared with chemoradiation only.

CONCLUSIONS

Surgery with systemic therapy delivered in a neoadjuvant or adjuvant fashion for patients with T3>7 cmN1 NSCLCs is associated with improvements in OS.

Cocaine impairs ovarian response to exogenous gonadotropins in nonhuman primates

OBJECTIVE

Determine whether cocaine directly impairs ovarian steroid production and ovulation.

METHODS

Normally cycling adult female rhesus monkeys received daily intravenous normal saline (control; n = 8) or cocaine (4 mg/kg; n = 8) through the follicular phase. Monkeys were injected daily with human menopausal gonadotropin (hMG; Pergonal) at a dose of 6 IU/kg intramuscularly beginning on cycle day 2. Daily blood samples were obtained, and serum estradiol (E(2)) and progesterone (P(4)) were measured by radioimmunoassay. When serum levels of E(2) declined, plateaued, or exceeded 600 pg/mL, laparoscopy was performed to count the number of follicles. If no new corpus luteum was present, monkeys were injected intramuscularly with 1000 IU of hCG. Laparoscopy was repeated 2 days later to document the number of ovulatory stigma.

RESULTS

During ovarian stimulation, cocaine-treated monkeys required an average additional 1.5 days of hMG injections (P =.01), and this resulted in a greater total dose of hMG compared with control monkeys (351 +/- 16 IU versus 297 +/- 15 IU [mean +/- standard error of the mean], P =.03). For spontaneous and hCG-triggered ovulation, the number of ovulatory stigma was significantly lower (P <.003) in the cocaine-treated versus control monkeys (16 versus 31). Peak E(2) levels were significantly (P =.05) lower in cocaine-treated monkeys compared with controls. Luteal phase P(4) levels were lower in the cocaine-treated monkeys, but the difference was not statistically significant when compared with controls.

CONCLUSION

Cocaine impaired ovarian responsiveness to exogenous gonadotropins and decreased ovulatory stigma in nonhuman primates. These findings suggest that cocaine has direct ovarian effects.

Anti-BB'-Sm antibodies, anticardiolipin antibodies, and thrombosis in systemic lupus erythematosus

OBJECTIVE

Anticardiolipin antibodies (aCL) are associated with thrombosis in patients with systemic lupus erythematosus (SLE). Our aim was to determine whether there is an association between aCL, anti-Sm antibodies, and thrombosis in patients with SLE.

METHODS

Sera from 153 patients with SLE were studied by ELISA, immunoblotting, and counter-immunoelectrophoresis (CIE) for anti-Sm antibodies, aCL and anti-dsDNA antibodies were detected by ELISA and radioimmunoassay, respectively.

RESULTS

Anti-Sm antibodies were detected in 62 patients (40.5%) by ELISA and in 16 (10.4%) by CIE; IgG-anti-BB'-Sm in 44 (28.7%) by immunoblotting; IgG-aCL in 82 (53.5%), IgM-aCL in 44 (28.7%), and anti-dsDNA antibodies in 128 (83.6%). Anti-Sm and anti-dsDNA antibodies were significantly more frequent in patients with than in patients without aCL. Of the 89 patients with aCL, 36 (40.4%) showed IgG-anti-BB'-Sm antibodies (OR: 4.7; 95% CI: 2-10.5). Thrombosis was present in 20 (22.4%) SLE patients with aCL and in two (3.1 %) SLE patients without aCL (OR: 8.9; 95% CI: 2.4-31.8). Of the 22 patients with thrombosis, five (22.7%) had precipitating anti-Sm antibodies (OR: 3.2; 95% CI: 1.04-9.8) and 14 (63.6%) showed IgG-anti-BB'-Sm antibodies (OR: 5.8; 95% CI: 2.3-14). Anti-BB'-Sm and aCL were significantly more frequent in patients with anti-dsDNA antibodies (32 and 62%) than in patients without these antibodies (12 and 36%) (OR: 3.4 and 2.9; 95% CI: 1.03-11.1 and 1.2-6.7, respectively).

CONCLUSION

IgG-anti-BB'-Sm antibodies are associated with aCL, anti-dsDNA, and thrombosis in patients with SLE. Our findings suggest a possible association between anti-Sm, anti-dsDNA, and aCL responses in these patients.

Simultaneous occurrence of diffuse idiopathic skeletal hyperostosis and ankylosing spondylitis

To the best of our knowledge, 10 cases of Ankylosing Spondylitis (AS) and Diffuse Idiopathic Skeletal Hyperostosis (DISH) coexisting in the same patient have been reported. A new case was found in a female patient at Los Angeles Medical Center in 1993, which we report in this paper. We also review the literature (Medline 1970-1994) and analyze the features of the reported cases. In order to study the incidence of this association in our population we have reviewed 106 cases of AS for radiological features of DISH. We found only one case.

CONCLUSION

this is a rare association with an incidence of 0.94% in our patients with AS. From the known cases, patients showing this association present clinically mild AS in which radiologic findings are the basis for the diagnosis. Finally we question the validity of excluding the diagnosis of DISH in patients with radiological features of sacroiliac ankylosis.

Heterogeneity of the anti-Ro(SSA) response in rheumatic diseases

OBJECTIVE

The immune response to the Ro(SSA) antigen is heterogeneous. Anti-Ro(SSA) positive sera may contain antibodies recognizing either a 60 or a 52 kDa polypeptide component of the Ro(SSA) particle. Thus we sought to determine the profile of anti-Ro(SSA) antibodies defined by immunoblotting in patients with rheumatic diseases.

METHODS

Immunoblotting against human placenta extract and ELISA against recombinant Ro(SSA) antigen as confirmatory tests were done to detect anti-Ro(SSA) antibodies in 563 sera from patients with systemic lupus erythematosus (SLE). Sjögren's syndrome (SS), rheumatoid arthritis (RA) and other connective tissue diseases.

RESULTS

Anti-52 kDa antibodies were more common in primary patients with SS (9/22; 40.9%) than in patients with SLE (29/135; 21.4%) or patients with RA (7/315; 2.2%). Anti-60 kDa antibodies were more frequent in patients with SLE (26/135; 19.2%) than in patients with primary SS (2/22; 9%) or RA (17/315; 5.3%). None of the 22 patients with primary SS had only antibodies to the 60 kDa polypeptide. Among the 153 patients whose sera were positive by ELISA, 73 (47.7%) were negative by immunoblotting. The most frequent diagnoses in these sera were RA and SLE. The anti-52 kDa sera had higher optical density values compared to anti-60 kDa sera.

CONCLUSIONS

Our observations indicate the existence of qualitatively and quantitatively different anti-Ro(SSA) responses in the rheumatic diseases. The major responses are anti-52 kDa antibodies in primary SS, both anti-52 and anti-60 kDa antibodies in SLE, and anti-60 kDa antibodies in RA and other connective tissue diseases.

Surgically induced endometriosis does not alter peritoneal factors in the rabbit model

OBJECTIVE

It was the purpose of this study to examine the cause and effect relationship between alterations in peritoneal factors and the presence of ectopic endometrium in the rabbit model.

DESIGN

Forty rabbits had autologous endometrial or omental (control) tissue surgically implanted. Peritoneal fluid (PF) volume, macrophage number, and macrophage activation, as well as the number of implants with adhesions, were compared with values obtained during the initial surgery. The effect of hormonal treatment on these factors was evaluated at a third laparotomy.

RESULTS

There was a significant increase (P less than 0.05) of adhesions in animals with endometrial implants. Peritoneal fluid volume, macrophage number, or macrophage activation were not increased in rabbits with endometrial implants as compared with controls, nor was there a response to hormonal manipulation.

CONCLUSIONS

These results demonstrate that PF volume, macrophage number, and macrophage activation are not altered by endometrial implants in the rabbit model. This suggests that the increase in these peritoneal factors in women with endometriosis may not be caused exclusively by the presence of ectopic endometrial tissue.