Insights into pelvic insufficiency fracture following pelvic radiotherapy for cervical cancer: a comparative review

BACKGROUND

Radiotherapy (RT)-induced pelvic insufficiency fractures (PIF) are prevalent in patients with cervical cancer. Inconclusive studies on PIF after cervical irradiation create uncertainty. This review examined PIF after RT in cervical patients, including its pathobiology, likely locations of fractures, incidence, clinical symptoms, and predisposing factors. We further discussed study limitations and therapeutic possibilities of PIF.

METHODS

The following online resources were searched for relevant articles: Google Scholar and PubMed. The keywords 'pelvic insufficiency fractures', 'cervical carcinoma' and 'cervical cancer', as well as 'chemoradiotherapy', 'chemoradiation', and 'radiotherapy', were some of the terms that were used during the search.

RESULTS

Patients with PIF report pelvic pain after radiation treatment for cervical cancer; the incidence of PIF ranges from 1.7 to 45.2%. Evidence also supports that among all patients treated with pelvic radiation, those who experienced pelvic insufficiency fractures invariably had at least one sacral fracture, making it the most frequently fractured bone in the body. Menopausal status, weight, BMI, age, and treatments and diagnosis modalities can influence PIF during radiotherapy.

CONCLUSIONS

In conclusion, our comparative review of the literature highlights significant heterogeneity in various aspects of PIF following radiation for patients with cervical cancer. This diversity encompasses prevalence rates, associated risk factors, symptoms, severity, diagnosis methods, preventive interventions, and follow-up periods. Such diversity underscores the complexity of PIF in this population and emphasizes the critical need for further research to elucidate optimal management strategies and improve patient outcomes.

Dosimetric evaluation of ovaries and pelvic bones associated with clinical outcomes in patients receiving total body irradiation with ovarian shielding

Total body irradiation (TBI) with ovarian shielding is expected to preserve fertility among hematopoietic stem cell transplant (HSCT) patients with myeloablative TBI-based regimens. However, the radiation dose to the ovaries that preserves ovarian function in TBI remains poorly understood. Furthermore, it is uncertain whether the dose to the shielded organs is associated with relapse risk. Here, we retrospectively evaluated the relationship between fertility and the dose to the ovaries, and between relapse risk and the dose to the pelvic bones. A total of 20 patients (median age, 23 years) with standard-risk hematologic diseases were included. Median follow-up duration was 31.9 months. The TBI prescribed dose was 12 Gy in six fractions for three days. Patients' ovaries were shielded with cylinder-type lead blocks. The dose-volume parameters (D98% and Dmean) in the ovaries and the pelvic bones were extracted from the dose-volume histogram (DVH). The mean ovary Dmean for all patients was 2.4 Gy, and 18 patients recovered menstruation (90%). The mean ovary Dmean for patients with menstrual recovery and without recovery were 2.4 Gy and 2.4 Gy, respectively, with no significant difference (P = 0.998). Hematological relapse was observed in five patients. The mean pelvis Dmean and pelvis D98% for relapse and non-relapse patients were 11.6 Gy and 11.7 Gy and 5.6 Gy and 5.3 Gy, respectively. Both parameters showed no significant difference (P = 0.827, 0.807). In conclusion, TBI with ovarian shielding reduced the radiation dose to the ovaries to 2.4 Gy, and preserved fertility without increasing the risk of relapse.

Predictive factors of posttreatment fracture by definitive radiotherapy for uterine cervical cancer

PURPOSE

Fractures are known to shorten life expectancy and worsen the quality of life. The risk of fractures after radiation therapy in cervical cancer patients is known to be multifactorial. In this study, we examined risk factors for fractures in cervical cancer patients, especially by evaluating bone densities and DVH parameters for fractured bones.

MATERIALS AND METHODS

For 42 patients, clinical characteristics, pretreatment CT bone densities, and radiation dose were compared between patients with and without fractures.

RESULTS

Posttreatment fractures occurred in 25 bones among ten patients. Pretreatment CT bone densities were significantly lower in patients with fractures (P < 0.05-0.01 across sites, except for the ilium and the ischium). Although DVH parameters were also significantly associated with fractures in univariate analysis, only CT densities were significantly associated with fractures in multivariate analysis.

CONCLUSION

Pretreatment CT densities of spinal and pelvic bones, which may reflect osteoporosis, have a significant impact on the risk for posttreatment fractures.

An easy way to determine bone mineral density and predict pelvic insufficiency fractures in patients treated with radiotherapy for cervical cancer

Purpose

The aim of this study was to investigate whether bone mineral density (BMD) as measured in planning computed tomographies (CTs) by a new method is a risk factor for pelvic insufficiency fractures (PIF) after radio(chemo)therapy (R(C)T) for cervical cancer.

Methods

62 patients with cervical cancer who received definitive or adjuvant radio(chemo)therapy between 2013 and 2017 were reviewed. The PIF were detected on follow-up magntic resonance imaging (MRI). The MRI of the PIF patients was registered to the planning CT and the PIF contoured. On the contralateral side of the fracture, a mirrored structure of the fracture was generated (mPIF). For the whole sacral bone, three lumbar vertebrae, the first and second sacral vertebrae, and the PIF, we analyzed the BMD (mg/cm³), V50Gy, Dmean, and Dmax.

Results

Out of 62 patients, 6 (9.7%) had a fracture. Two out of the 6 patients had a bilateral fracture with only one of them being symptomatic. PIF patients showed a significantly lower BMD in the sacral and the lumbar vertebrae (p < 0.05). The BMD of the contoured PIF, however, when comparing to the mPIF, did not reach significance (p < 0.49). The difference of the V50Gy of the sacrum in the PIF group compared to the other (OTH) patients, i.e. those without PIF, did not reach significance.

Conclusion

The dose does not seem to have a relevant impact on the incidence of PIF in our patients. One of the predisposing factors for developing PIF after radiotherapy seems to be the low BMD. We presented an easy method to assess the BMD in planning CTs.

Comparison of prostate verification with implanted gold markers in tissue surrounding the prostate and pelvic bony anatomy for external beam radiation therapy following low-dose-rate brachytherapy: a prospective clinical trial

We aimed to investigate whether gold marker implantation in the tissue surrounding the prostate could accurately monitor setup errors during external beam radiation therapy (EBRT) following low-dose-rate (LDR) brachytherapy. Thirty-eight patients had confirmed intermediate- or high-risk prostate cancer and received EBRT following LDR brachytherapy. In >175 computed tomography imaging sessions, the average values of the weekly setup error during EBRT to the prostate centroid at the time of gold marker matching in the surrounding tissue of the prostate and pelvic bone matching were measured and then compared using the Wilcoxon signed-rank test. Gold marker matching in the surrounding tissue of the prostate estimated setup errors better than those estimated by bone matching (3D displacement = 2.7 ± 2.0 vs 3.8 ± 2.6 mm, P < 0.01). Overall, the standard deviation of systematic (Σ) and random (σ) setup error was lower with gold marker matching than with bone matching (3D displacement = 1.8 and 1.1 mm vs 2.1 and 1.6 mm, respectively). With gold marker matching, the setup error of the position of the prostate centroid was smaller, and the optimal setup margin was lower than that with bone matching (2Σ + 0.7σ and 2.5Σ + 0.7σ of 3D displacement = 4.3 and 5.2 mm vs 5.3 and 6.4 mm, respectively). This high-precision radiotherapy approach placing gold markers in the surrounding tissue of the prostate can allow more accurate setup during EBRT following LDR brachytherapy.

[Extracorporeal irradiation : Reimplantation of bone segments in the treatment of malignant bone tumours]

BACKGROUND

Malignant bone tumors themselves and the wide resection required because of them may cause huge bone defects in the bone segment involved. Autologous bone grafts are a reliable option to cover these defects in many cases but their availability is limited. Besides common alternative reconstruction methods, including the use of allografts and/or prostheses, especially extracoroporeal irradiation (ECI) and reimplantation of the bone segment involved is attracting increasingly more attention nowadays.

DISCUSSION

In the following, we report on indications/contraindications, details of the operative technique, as well as the recommended rehabilitation regime of ECI. Furthermore, we compare our own results with those published in the recent literature. Especially the advantages and disadvantages of this method, the risks and the complications are illustrated and critically discussed.

CONCLUSION

Extracorporeal irradiation of a tumor bearing bone segment is a valuable alternative reconstruction technique following tumor resections of the pelvis, femur and tibia, with encouraging results with respect to local control, complication risks and functional outcome.

Poor Utility of Gonadal Shielding for Pediatric Pelvic Radiographs

Plain pelvic radiographs are commonly used for a variety of pediatric orthopedic disorders. Lead shielding is typically placed over the gonads to minimize radiation exposure to these sensitive tissues. However, misplaced shielding can sabotage efforts to protect patients from excessive radiation exposure either by not covering radiosensitive tissues or by obscuring anatomic areas of interest, prompting repeat radiographic examinations. The goal of this study was to determine the incidence of misplaced shielding for pelvic radiographs obtained for pediatric orthopedic evaluation. Children 8 to 16 years old who had an anteroposterior or frog lateral pelvic radiograph between 2008 and 2014 were included. A total of 3400 patients met the inclusion criteria, and 84 boys and 84 girls were randomly selected for review. For both boys and girls, the percentage of incorrectly positioned or missing shields was calculated. Chi-square testing was used to compare the frequency of missing or incorrectly placed shields between sexes and age groups. Pelvic shields were misplaced in 49% of anteroposterior and 63% of frog lateral radiographs. Shielding was misplaced more frequently for girls than for boys on frog lateral radiographs (76% vs 51%; P<.05). Pelvic bony landmarks were often obscured by pelvic shielding, with a frequency of 7% to 43%, depending on the specific landmark. The femoral head and acetabulum were obscured by shielding in up to 2% of all images. The findings suggest that accepted pelvic shielding protocols are ineffective. Consideration should be given to alternative protocols or abandonment of this practice. [Orthopedics. 2017; 40(4):e623-e627.].

Bone texture analysis using CT-simulation scans to individuate risk parameters for radiation-induced insufficiency fractures

This study deals with the role of texture analysis as a predictive factor of radiation-induced insufficiency fractures in patients undergoing pelvic radiation.

INTRODUCTION

This study aims to assess the texture analysis (TA) of computed tomography (CT) simulation scans as a predictive factor of insufficiency fractures (IFs) in patients with pelvic malignancies undergoing radiation therapy (RT).

METHODS

We performed an analysis of patients undergoing pelvic RT from January 2010 to December 2014, 24 of whom had developed pelvic bone IFs. We analyzed CT-simulation images using ImageJ macro software and selected two regions of interest (ROIs), which are L5 body and the femoral head. TA parameters included mean (m), standard deviation (SD), skewness (sk), kurtosis (k), entropy (e), and uniformity (u). The IFs patients were compared (1:2 ratio) with controlled patients who had not developed IFs and matched for sex, age, menopausal status, type of tumor, use of chemotherapy, and RT dose. A reliability test of intra- and inter-reader ROI TA reproducibility with the intra-class correlation coefficient (ICC) was performed. Univariate and multivariate analyses (logistic regression) were applied for TA parameters observed both in the IFs and the controlled groups.

RESULTS

Inter- and intra-reader ROI TA was highly reproducible (ICC > 0.90). Significant TA parameters on paired t test included L5 m (p = 0.001), SD (p = 0.002), k (p = 0.006), e (p = 0.004), and u (p = 0.015) and femoral head m (p < 0.001) and SD (p = 0.001), whereas on logistic regression analysis, L5 e (p = 0.003) and u (p = 0.010) and femoral head m (p = 0.027), SD (p = 0.015), and sex (p = 0.044).

CONCLUSIONS

In our experience, bone CT TA could be correlated to the risk of radiation-induced IFs. Studies on a large patient series and methodological refinements are warranted.

Irradiation of anatomically defined pelvic subsites and acute hematologic toxicity in anal cancer patients undergoing chemoradiation

PURPOSE

Chemoradiation for the treatment of anal cancer is known to cause significant hematologic toxicity (HT). We sought to investigate if radiation dose to specific pelvic subsites is associated with increased HT risk.

METHODS AND MATERIALS

Forty-five patients with nonmetastatic anal cancer who received definitive chemoradiation with intensity modulated radiation therapy and concurrent mitomycin-C and 5-fluorouracil were studied. Total pelvic bone marrow (TBM) was divided into 3 subsites: lumbosacral bone marrow (LSBM), including the entire sacrum and L5 vertebral body; iliac bone marrow (IBM) extending from the iliac crests to the superior border of the femoral head; and lower pelvic bone marrow, including the pubic bones, ischia, acetabula, and proximal femurs. The primary endpoint was absolute neutrophil count (ANC) nadir during or within 2 weeks of treatment completion. Generalized linear modeling was used to analyze the correlation between the equivalent uniform dose (with an "a" value of 0.5) to the individual pelvic subsites and the various hematologic endpoints. Age, body mass index, sex, baseline blood counts, and immunosuppression were analyzed as potential covariates.

RESULTS

Mean ± standard deviation ANC nadir was 0.77 × 10⁹/L (±0.66 × 10⁹/L). Grades 3+ and 4+ neutropenia occurred in 71.1% and 44.4% of patients, respectively. In addition to radiation dose to pelvic bone marrow, baseline ANC was the only significant predictor of hematologic toxicity on multivariable analysis and was included in all models. The equivalent uniform doses of TBM, LSBM, and IBM were each significantly associated with neutropenia. The model performance of TBM (adjusted R² = 0.226) was similar to both LSBM (adjusted R² = 0.206) and IBM (adjusted R² = 0.249).

CONCLUSIONS

Radiation doses to TBM, LSBM, and IBM were individually associated with HT, suggesting that sparing just a portion of pelvic bone marrow is insufficient to decrease rates of clinically significant bone marrow suppression.

Dose to specific subregions of pelvic bone marrow defined with FDG-PET as a predictor of hematologic nadirs during concomitant chemoradiation in anal cancer patients

To test the hypothesis that irradiated volume of specific subregions of pelvic active bone marrow as detected by (18)FDG-PET may be a predictor of decreased blood cells nadirs in anal cancer patients undergoing concurrent chemoradiation, we analyzed 44 patients submitted to IMRT and concurrent chemotherapy. Several bony structures were defined: pelvic and lumbar-sacral (LSBM), lower pelvis (LPBM) and iliac (IBM) bone marrow. Active BM was characterized employing (18)FDG-PET and characterized in all subregions as the volume having standard uptake values (SUVs) higher than SUVmean. All other regions were defined as inactive BM. On dose-volume histograms, dosimetric parameters were taken. Endpoints included white blood cell count (WBC), absolute neutrophil count (ANC), hemoglobin (Hb) and platelet (Plt) nadirs. Generalized linear modeling was used to find correlations between dosimetric variables and blood cells nadirs. WBC nadir was significantly correlated with LSBM mean dose (β = -1.852; 95 % CI -3.205/-0.500; p = 0.009), V10 (β = -2.153; 95 % CI -4.263/-0.721; p = 0.002), V20 (β = -2.081; 95 % CI -4.880/-0.112; p = 0.003), V30 (β = -1.971; 95 % CI -4.748/-0.090; p = 0.023) and IBM V10 (β = -0.073; 95 % CI -0.106/-0.023; p = 0.016). ANC nadir found to be significantly associated with LSBM V10 (β = -1.878; 95 % CI -4.799/-0.643; p = 0.025), V20 (β = -1.765; 95 % CI -4.050/-0.613; p = 0.030) and IBM V10 (β = -0.039; 95 % CI -0.066/-0.010; p = 0.027). Borderline significance was found for correlation between Plt nadir and LSBM V30 (β = -0.056; 95 % CI -2.748/-0.187; p = 0.060), V40 (β = -0.059; 95 % CI -3.112/-0.150; p = 0.060) and IBM V30 (β = -0.028; 95 % CI -0.074/-0.023; p = 0.056). No inactive BM subsites were found to be correlated with any blood cell nadir. (18)FDG-PET is able to define active bone marrow within pelvic osseous structures. LSBM is the strongest predictor of decreased blood cells nadirs in anal cancer patients undergoing concurrent chemoradiation.

Long-Term Bone Marrow Suppression During Postoperative Chemotherapy in Rectal Cancer Patients After Preoperative Chemoradiation Therapy

PURPOSE/OBJECTIVE(S)

To quantify ensuing bone marrow (BM) suppression during postoperative chemotherapy resulting from preoperative chemoradiation (CRT) therapy for rectal cancer.

METHODS AND MATERIALS

We retrospectively evaluated 35 patients treated with preoperative CRT followed by postoperative 5-Fluorouracil and oxaliplatin (OxF) chemotherapy for locally advanced rectal cancer. The pelvic bone marrow (PBM) was divided into ilium (IBM), lower pelvis (LPBM), and lumbosacrum (LSBM). Dose volume histograms (DVH) measured the mean doses and percentage of BM volume receiving between 5-40 Gy (i.e.: PBM-V5, LPBM-V5). The Wilcoxon signed rank tests evaluated the differences in absolute hematologic nadirs during neoadjuvant vs. adjuvant treatment. Logistic regressions evaluated the association between dosimetric parameters and ≥ grade 3 hematologic toxicity (HT3) and hematologic event (HE) defined as ≥ grade 2 HT and a dose reduction in OxF. Receiver Operator Characteristic (ROC) curves were constructed to determine optimal threshold values leading to HT3.

RESULTS

During OxF chemotherapy, 40.0% (n=14) and 48% (n=17) of rectal cancer patients experienced HT3 and HE, respectively. On multivariable logistic regression, increasing pelvic mean dose (PMD) and lower pelvis mean dose (LPMD) along with increasing PBM-V (25-40), LPBM-V25, and LPBM-V40 were significantly associated with HT3 and/or HE during postoperative chemotherapy. Exceeding ≥36.6 Gy to the PMD and ≥32.6 Gy to the LPMD strongly correlated with causing HT3 during postoperative chemotherapy.

CONCLUSIONS

Neoadjuvant RT for rectal cancer has lasting effects on the pelvic BM, which are demonstrable during adjuvant OxF. Sparing of the BM during preoperative CRT can aid in reducing significant hematologic adverse events and aid in tolerance of postoperative chemotherapy.

Dose-volume effects for pelvic bone marrow in predicting hematological toxicity in prostate cancer radiotherapy with pelvic node irradiation

PURPOSE

To prospectively identify clinical/dosimetric predictors of acute/late hematologic toxicity (HT) in chemo-naÏve patients treated with whole-pelvis radiotherapy (WPRT) for prostate cancer.

MATERIAL AND METHODS

Data of 121 patients treated with adjuvant/salvage WPRT were analyzed (static-field IMRT n=19; VMAT/Rapidarc n=57; Tomotherapy n=45). Pelvic bone marrow (BM) was delineated as ilium (IL), lumbosacral, lower and whole pelvis (WP), and the relative DVHs were calculated. HT was graded both according to CTCAE v4.03 and as variation in percentage relative to baseline. Logistic regression was used to analyze association between HT and clinical/DVHs factors.

RESULTS

Significant differences (p<0.005) in the DVH of BM volumes between different techniques were found: Tomotherapy was associated with larger volumes receiving low doses (3-20 Gy) and smaller receiving 40-50 Gy. Lower baseline absolute values of WBC, neutrophils and lymphocytes (ALC) predicted acute/late HT (p ⩽ 0.001). Higher BM V40 was associated with higher risk of acute Grade3 (OR=1.018) or late Grade2 lymphopenia (OR=1.005). Two models predicting lymphopenia were developed, both including baseline ALC, and BM WP-V40 (AUC=0.73) and IL-V40+smoking (AUC=0.904) for acute/late respectively.

CONCLUSIONS

Specific regions of pelvic BM predicting acute/late lymphopenia, a risk factor for viral infections, were identified. The 2-variable models including specific constraints to BM may help reduce HT.

Modeling early haematologic adverse events in conformal and intensity-modulated pelvic radiotherapy in anal cancer

Background and purpose

To determine if there are differences between dose to pelvic bone marrow (PBM) using intensity modulated radiotherapy (IMRT) under UK guidance versus conformal radiotherapy (CRT) per ACT II protocol and if differences translate to rates of early haematological adverse events grade 3 or greater (HT3+).

Methods and materials

Two groups of 20+ patients, treated under IMRT and CRT regimes respectively, were identified. All patients underwent weekly blood cell count: haemoglobin (HgB), white cell count (WCC), absolute neutrophil count (ANC) and platelets (plats).

Percent volume of PBM and sub structures receiving 5–25 Gy were tested for statistical significance. Regression models were used to test for correlation to blood counts. NTCP modeling was also performed.

Results

PMB dose metrics showed a significant increase in the IMRT group. Regression analysis showed iliac and lumbosacral PBM dose metrics to associate with reduced nadir ANC and WCC. NTCP at HT3+ was 0.13 using IMRT relative to 0.07 using CRT (p < 0.05).

Conclusion

Whilst this is a relatively small retrospective study and lacks information on the distribution of active PBM, IMRT treatment has been shown to significantly increase PMB irradiation. PBM dose metrics have been shown to be predictive of WCC and ANC suppression. NTCP modeling predicts much high risk of HT3+. Paradoxically, actual rates of HT3+ were comparable suggesting that differences in the distributions of dose metrics maybe a significant factor and/or that there are insufficiency in the NTCP modeling.

Pelvic insufficiency fracture after definitive radiotherapy for uterine cervical cancer: retrospective analysis of risk factors

The purpose of this study is to determine the incidence, clinical characteristics and risk factors of postradiation pelvic insufficiency fracture (PIF) in women with uterine cervical cancer. We reviewed the medical records of 126 patients who received definitive radiotherapy (RT) for uterine cervical cancer between 2003 and 2009 at our institution. Among them, 99 patients who underwent at least one computed tomography (CT) or magnetic resonance imaging of the pelvis during their follow-up at more than 6 months were included in this analysis. The relationship between the incidence of PIF and several patient- and treatment-related factors was analyzed. The median follow-up period was 21 months. Of the 126 patients, 33 (with a total of 50 lesions) were diagnosed with PIF. The 2-year cumulative incidence was 32%. Univariate analysis showed that age ≥70 years (P= 0.0010), postmenopausal state (P = 0.0013), and lower CT density of bone and bone marrow (P= 0.020) significantly related to PIF. In a multivariate analysis, of the 59 patients whose CT densities were evaluable, lower CT density was the only significant factor associated with PIF (P = 0.0026). In conclusion, postradiation PIFs were detected in a considerable number of patients after definitive RT for cervical cancer. Predisposing factors were older age, postmenopausal state, and decreased density of bone and bone marrow on CT.

Hematologic toxicity in RTOG 0418: a phase 2 study of postoperative IMRT for gynecologic cancer

PURPOSE

Intensity modulated radiation therapy (IMRT), compared with conventional 4-field treatment, can reduce the volume of bone marrow irradiated. Pelvic bone marrow sparing has produced a clinically significant reduction in hematologic toxicity (HT). This analysis investigated HT in Radiation Therapy Oncology Group (RTOG) 0418, a prospective study to test the feasibility of delivering postoperative IMRT for cervical and endometrial cancer in a multiinstitutional setting.

METHODS AND MATERIALS

Patients in the RTOG 0418 study were treated with postoperative IMRT to 50.4 Gy to the pelvic lymphatics and vagina. Endometrial cancer patients received IMRT alone, whereas patients with cervical cancer received IMRT and weekly cisplatin (40 mg/m(2)). Pelvic bone marrow was defined within the treatment field by using a computed tomography density-based autocontouring algorithm. The volume of bone marrow receiving 10, 20, 30, and 40 Gy and the median dose to bone marrow were correlated with HT, graded by Common Terminology Criteria for Adverse Events, version 3.0, criteria.

RESULTS

Eighty-three patients were eligible for analysis (43 with endometrial cancer and 40 with cervical cancer). Patients with cervical cancer treated with weekly cisplatin and pelvic IMRT had grades 1-5 HT (23%, 33%, 25%, 0%, and 0% of patients, respectively). Among patients with cervical cancer, 83% received 5 or more cycles of cisplatin, and 90% received at least 4 cycles of cisplatin. The median percentage volume of bone marrow receiving 10, 20, 30, and 40 Gy in all 83 patients, respectively, was 96%, 84%, 61%, and 37%. Among cervical cancer patients with a V40 >37%, 75% had grade 2 or higher HT compared with 40% of patients with a V40 less than or equal to 37% (P =.025). Cervical cancer patients with a median bone marrow dose of >34.2 Gy also had higher rates of grade ≥ 2 HT than did those with a dose of ≤ 34.2 Gy (74% vs 43%, P=.049).

CONCLUSIONS

Pelvic IMRT with weekly cisplatin is associated with low rates of HT and high rates of weekly cisplatin use. The volume of bone marrow receiving 40 Gy and the median dose to bone marrow correlated with higher rates of grade ≥ 2 toxicity among patients receiving weekly cisplatin (cervical cancer patients). Evaluation and limitation of the volume of bone marrow treated with pelvic IMRT is warranted in patients receiving concurrent chemotherapy.

Impact of bone marrow radiation dose on acute hematologic toxicity in cervical cancer: principal component analysis on high dimensional data

PURPOSE

To study the effects of increasing pelvic bone marrow (BM) radiation dose on acute hematologic toxicity in patients undergoing chemoradiotherapy, using a novel modeling approach to preserve the local spatial dose information.

METHODS AND MATERIALS

The study included 37 cervical cancer patients treated with concurrent weekly cisplatin and pelvic radiation therapy. The white blood cell count nadir during treatment was used as the indicator for acute hematologic toxicity. Pelvic BM radiation dose distributions were standardized across patients by registering the pelvic BM volumes to a common template, followed by dose remapping using deformable image registration, resulting in a dose array. Principal component (PC) analysis was applied to the dose array, and the significant eigenvectors were identified by linear regression on the PCs. The coefficients for PC regression and significant eigenvectors were represented in three dimensions to identify critical BM subregions where dose accumulation is associated with hematologic toxicity.

RESULTS

We identified five PCs associated with acute hematologic toxicity. PC analysis regression modeling explained a high proportion of the variation in acute hematologicity (adjusted R(2), 0.49). Three-dimensional rendering of a linear combination of the significant eigenvectors revealed patterns consistent with anatomical distributions of hematopoietically active BM.

CONCLUSIONS

We have developed a novel approach that preserves spatial dose information to model effects of radiation dose on toxicity, which may be useful in optimizing radiation techniques to avoid critical subregions of normal tissues. Further validation of this approach in a large cohort is ongoing.

The benefit of small bowel and pelvic bone sparing in excluding common iliac lymph node region from conventional radiation fields in patients with uterine cervical cancer: a dosimetric study

The purpose of this study was to compare dose reduction to the small bowel and sacral bone by two-field and four-field techniques when the common iliac lymph node region is excluded from the radiation field in external beam radiotherapy of uterine cervical cancer. Thirteen patients with cervical cancer were entered into the study. Conventional treatment plans based on bony landmarks were made with parallel-opposed two-field technique (C2F) and four-field box technique (C4F). Modified C2F (M2F) and C4F (M4F) plans of excluding the common iliac lymph node region from the conventional radiation fields were created in reference to the bifurcations of pelvic arteries in computed tomography images. For each patient, the dose volume histograms for the small bowel and sacral bone resulting from the C2F, C4F, M2F, and M4F plans were compared. The volumes were obtained at 10 levels of prescribed dose, at increments of 10%, from 5 Gy to 50 Gy. By sparing both small bowel and sacral bone, the M2F and M4F plans were significantly better than the C2F and C4F plans at any dose level (p < 0.05), respectively. In addition, the M4F plan was significantly better than the M2F plan in sparing both small bowel at 10-50% of the prescribed dose (p < 0.05) and sacral bone at 40-100% of the prescribed dose (p < 0.05). The present study suggests that modified treatment planning could be useful for selected patients for reducing small bowel complications and insufficiency fracture after radiotherapy.

Estimating differences in volumetric flat bone growth in pediatric patients by radiation treatment method

PURPOSE

To estimate potential differences in volumetric bone growth in children with sarcoma treated with intensity-modulated (IMRT) and conformal (CRT) radiation therapy using an empiric dose-effect model.

METHODS AND MATERIALS

A random coefficient model was used to estimate potential volumetric bone growth of 36 pelvic bones (ischiopubis and ilium) from 11 patients 4 years after radiotherapy. The model incorporated patient age, pretreatment bone volume, integral dose >35 Gy, and time since completion of radiation therapy. Three dosimetry plans were entered into the model: the actual CRT/IMRT plan, a nontreated comparable IMRT/CRT plan, and an idealized plan in which dose was delivered only to the planning target volume. The results were compared with modeled normal bone growth.

RESULTS

The model predicted that by using the idealized, IMRT, and CRT approaches, patients would maintain 93%, 87%, and 84%, respectively (p = 0.06), of their expected normal growth. Patients older than 10 years would maintain 98% of normal growth, regardless of treatment method. Those younger than 10 years would maintain 87% (idealized), 76% (IMRT), or 70% (CRT) of their expected growth (p = 0.015). Post hoc testing (Tukey) revealed that the CRT and IMRT approaches differed significantly from the idealized one but not from each other.

CONCLUSIONS

Dose-effect models facilitate the comparison of treatment methods and potential interventions. Although treatment methods do not alter the growth of flat bones in older pediatric patients, they may significantly impact bone growth in children younger than age 10 years, especially as we move toward techniques with high conformity and sharper dose gradient.

Clinical application of a repositioning scheme, using gold markers and electronic portal imaging

BACKGROUND AND PURPOSE

To implement an on-line correction scheme based on implanted markers to reduce treatment margins in external beam radiation therapy (EBRT) of carcinoma of the prostate. In turn reduction in treatment margins reduces irradiated volumes and offers the possibility of reduced normal tissue complications or escalated target dose.

PATIENTS AND METHODS

Five or six gold markers were implanted in 10 patients treated for prostate carcinoma using EBRT. All patients were enlisted in an IRB-approved protocol. Before each fraction two portal images were obtained using a low dose (2MU). Positions of the markers were calculated from these images using an in-house developed program. Corrections were applied with a threshold of 2mm displacement. After correction the procedure was repeated.

RESULTS

Overall systematic errors were reduced from 7.45, 1.29, and 5.12 mm to 0.65, 0.11, and 0.46 mm in, respectively, the antero-posterior, lateral, and cranio-caudal directions. Likewise, the overall SD were reduced from 5.99, 5.34, and 4.44 mm to 2.82, 2.64, and 2.22 mm, respectively. All reductions were highly significant (P < 0.01) using a t-test for systematic and an F-test for random errors. On an individual level all but three patients showed significant improvements in all directions for the random errors. All patients improved in at least one direction. Systematic errors were significantly lower in all patients. Simulated correction schemes using this data suggest that margin reduction using off-line reduction does not benefit substantially from on-line corrections in the first few fractions.

CONCLUSIONS

Use of marker-based correction improves the patient position. Factors influencing the accuracy were: (1) number of seeds usable for correction, (2) distribution of markers throughout the volume of interest, and (3) objective instructions for patient realignment.

Symptomatic osteoradionecrosis of pelvic bones in patients with gynecological malignancies-result of a long-term follow-up

The aim of this study was to assess the incidence and risk factors of pelvic fractures as a result of radiation therapy in women with gynecological cancer. We retrospectively reviewed 3530 female patients treated at our institute between 1980 and 1998 with megavoltage radiation with or without brachytherapy for cancer in the pelvic area. Eligible were patients with vulvar, vaginal, cervical, endometrial, and fallopian tube cancer. Median follow-up was 88 months (range 0-240). Emphasis was put on treatment-related and patient-related risk factors. Of the eligible 3155 patients, 15 developed symptomatic bone fracture caused by osteoradionecrosis, which makes an overall incidence of 0.44% The diagnosis was based on anamnesis, clinical course, and X-ray or computed tomography images. Median time of onset was 44 months (range 6-197). All patients had pain as the first symptom. The only independent predictive factor for developing osteoradionecrosis seemed to be preexistent osteoporosis. Other risk factors that are related to osteoporosis include higher age, postmenopausal status, or steroid treatment. We did not find any significant treatment-related predictive factor for pelvic osteoradionecrosis. Patients with osteoporosis are probably at the highest risk for developing osteoradionecrotic fractures after pelvic radiotherapy. More studies are needed to find out other endogenous predictive factors.

Risk of pelvic fractures in older women following pelvic irradiation

CONTEXT

Pelvic fractures, including hip fractures, are a major source of morbidity and mortality in older women. Although therapeutic pelvic irradiation could increase the risk of such fractures, this effect has not been studied.

OBJECTIVE

To determine if women who undergo pelvic irradiation for pelvic malignancies (anal, cervical, or rectal cancers) have a higher rate of pelvic fracture than women with pelvic malignancies who do not undergo irradiation.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a retrospective cohort study using Surveillance, Epidemiology, and End Results (SEER) cancer registry data linked to Medicare claims data. A total of 6428 women aged 65 years and older diagnosed with pelvic malignancies from 1986 through 1999 were included. We compared results for women who did (n = 2855) vs did not (n = 3573) undergo radiation therapy. To assess the influence of selection bias, we also evaluated the effect of irradiation on osteoporotic fractures in nonirradiated sites (arm and spine).

MAIN OUTCOME MEASURE

We evaluated the effect of irradiation on the incidence of pelvic fractures over time, and adjusted for potential confounders using a proportional hazards model.

RESULTS

Women who underwent radiation therapy were more likely to have a pelvic fracture than women who did not undergo radiation therapy (cumulative 5-year fracture rate, 14.0% vs 7.5% in women with anal cancer, 8.2% vs 5.9% in women with cervical cancer, and 11.2% vs 8.7% in women with rectal cancer); the difference was statistically significant and most fractures (90%) were hip fractures. We controlled for potential confounders including age, race, cancer stage, and geographic location. The impact of irradiation varied by cancer site: treatment for anal cancer was associated with a higher risk of pelvic fractures (hazard ratio, 3.16; 95% confidence interval, 1.48-6.73); than for cervical cancer (hazard ratio, 1.66; 95% confidence interval, 1.06-2.59); or rectal cancer (hazard ratio, 1.65; 95% confidence interval, 1.33-2.05). No statistically significant difference was found in the rate of arm or spine fractures between the irradiated and nonirradiated groups (hazard ratio, 1.15; 95% confidence interval, 0.89-1.48).

CONCLUSIONS

Pelvic irradiation substantially increases the risk of pelvic fractures in older women. Given the high baseline risk of pelvic fracture, this finding is of particular concern.

[A fast procedure of patient set-up verification in pelvic radiotherapy]

Accuracy of patient positioning is an important aspect in radiation therapy. The present paper presents a new procedure for the determination of set-up errors in radiotherapy, which is based on a special form of the Fast Fourier Transform (FFT), i.e., the Fast Hartley Transform (FHT). The use of this method allows to compare in short time verification and simulator films, and to calculate the translation vector or the in-plane rotation of the patient. Standard deviations < 1 mm for shifting measurements and < 1 degree for measurements of the rotation were detected, provided that the positioning remained within the common clinical range. The present results were in good agreement with data obtained using a landmark-based method.

Pelvic insufficiency fractures after preoperative radiotherapy for rectal carcinoma

Insufficiency fractures of the pelvic bones are rare complications of radiotherapy, but they can cause significant morbidity. We report a patient who developed pelvic insufficiency fractures because of preoperative hypofractionated radiotherapy with chemotherapy for rectal carcinoma. She was treated with a four-field box technique, receiving 20 Gy in four fractions, and she underwent concurrent pharmacokinetic modulating chemotherapy (PMC; intravenous infusion of 5-fluorouracil [FU], 750 mg/body per 24 h and oral administration of uracil and futrafur [UFT] 400 mg/day) over a 1-week period. She developed severe buttock and femoral pain 10 months after this preoperative therapy. Physical examination at this time was unremarkable, with an absence of neurological signs, and radiographic examination was also normal, resulting in the patient initially being undiagnosed. However, 2 months after the onset of her initial pain, she was diagnosed as having pelvic insufficiency fractures on conventional radiographs. Although preoperative chemoradiotherapy has been widely accepted for improving local control and survival in patients with primary rectal carcinoma, surgeons need to be aware of this rare complication that can arise even 10 months after preoperative chemoradiotherapy.

Pelvic insufficiency fractures in postmenopausal woman with advanced cervical cancer treated by radiotherapy

PURPOSE

To assess the predisposing factors and clinical characteristics of pelvic insufficiency fractures (PIF) in postmenopausal women with pelvic irradiation.

MATERIAL AND METHODS

A total 335 postmenopausal patients with cervical cancer of the intact uterus treated with radiation therapy between 1983 and 1998 were reviewed. Total external dose was delivered between 45 and 50.4 Gy with parallel opposed anteroposterior portals. Total brachytherapy dose at point A was delivered between 10 and 36 Gy. PIF were diagnosed by bone scintigraphy and confirmed by computed tomography. The cumulative incidence of symptomatic PIF was estimated by actuarial methods. Potential risk factors (age, weight, type II diabetes, delivery, menopause, total external dose, total brachytherapy dose) were assessed.

RESULTS

Fifty-seven (17.0%) of 335 patients were diagnosed as having PIF. Forty-seven patients were symptomatic and ten were asymptomatic. Parameters carrying a significant association with PIF were body weight 49 kg or below (P=0.044) in stepwise logistic regression analysis. The cumulative incidence of symptomatic PIF at 5 years was 17.9% calculated by the Kaplan-Meier method. A body weight of 49 kg or below and more than three deliveries were identified as having a significant effect on symptomatic PIF in univariate analysis (P=0.021, P=0.003, log-rank test) and Cox life table regression analysis (P=0.038, P=0.013). Five patients required narcotic agents and eight patients required hospital admission.

CONCLUSIONS

We should consider reducing the dose contribution to the sacrum and sacroilac joints, without underdosing the tumor, especially in postmenopausal women with many deliveries or low body weight.

Multimodal therapy for the treatment of nonmetastatic Ewing sarcoma of pelvis

The purpose of this study was to evaluate the outcome of patients with Ewing sarcoma (ES) of the pelvis, attempting to identify prognostic factors to select patients for more aggressive treatment. Seventy-seven patients with nonmetastatic ES of the pelvis were treated at Rizzoli Institute between 1979 and 1996. Four different protocols of chemotherapy were used successively. Two protocols consisted of VACAc, and two of VACAc plus ifosfamide and etoposide. Local treatment consisted of surgery in 5 patients, radiotherapy in 60, and surgery followed by radiotherapy in 12. Mean follow-up was 11 years (range 5-25 years). Thirty-three patients remained continuously free of disease; 43 relapsed (24 due to metastases and 19 to local recurrence and metastases); 1 died of treatment-related complications. The 5- and 10-year event-free survival rates were 45% and 44%, respectively, and the 5- and 10-year overall survival rates were 48 and 44. These results are significantly worse than the ones achieved in 329 contemporary patients with extrapelvic lesions treated with the same protocols of chemotherapy (5- and 10-year event-free survival = 46% vs. 64% and 44% vs. 69%). Thus, despite associated chemotherapy, the outcome of ES localized in the pelvis remains poor, and new innovative methods for the treatment of this tumor are needed.

Pelvic insufficiency fracture after pelvic irradiation in uterine cervix cancer

OBJECTIVES

Pelvic insufficiency fractures (IF) are well known but uncommon and are frequently misinterpreted sequelae. The clinical features were investigated.

METHODS

Four hundred sixty-three patients, who were treated between 1994 and 2000 for uterine cervix cancer, were clinically examined. All patients had been treated with 10 or 15 MV photons, with 50.4-55.8 Gy in 28 fractions with adjuvant intent (n = 235) in addition to high-dose-rate brachytherapy 24 Gy in 6 fractions for curative treatment (n = 228). The median follow-up was 38 months.

RESULTS

Eight patients (8/463, 1.7%) developed pelvic IF 7-19 months (median, 12 months) after the treatment. Among these, seven patients (7/228, 3.1%) were treated with curative intent and one (1/235, 0.4%) was treated with adjuvant intent. All patients were postmenopausal and complained of moderate to severe pelvic pain, which resolved after 1-11 months with conservative therapy in all patients. Two of these patients also had radiation proctitis.

CONCLUSION

In women who present with pelvic pain after radiotherapy for cervical cancer, bony destruction and fractures may be indicative of a late radiation effect rather than osseous metastasis. IF are more common in the curative treatment group than in the postoperative adjuvant group.

Extracorporeally irradiated autografts in pelvic reconstruction after malignant tumour resection

We treated 15 patients suffering from an extracompartmental malignant pelvic tumour by resecting the affected part of the bone, irradiating it extracorporeally with 300 Gy, and reimplanting it after having removed the bulk of the lesion. Adjuvant therapies were used according to the type and extension of the tumour. Follow-up was an average of 4 years 6 months. Complications were seen in 13 patients. Most mechanical complications were related to the use of hip arthroplasties. Internal fixation of the graft failed in one case only, infection was seen in three cases, and seven patients died after local recurrence. Functional scores were fair. Although many complications were seen, this method remains our treatment of choice.

MR imaging characteristics of osteoradionecrosis of the pelvis after radiation therapy on gynecological tumors

PURPOSE

To describe MR imaging characteristics of osteoradionecrosis (ORN) of the pelvis as a result of radiation therapy (RT) on gynecological tumors.

MATERIAL AND METHODS

Radiography, computed tomography (CT) and magnetic resonance imaging (MRI) were performed on 9 women (mean age 67.5 years) with gynecological tumors to identify ORN. T1- and T2-weighted sequences and contrast-enhanced t1-weighted sequences with and without fat saturation were used. The patients began developing pain after the completion of RT indicating a possible ORN a which time MRI was performed. MR images were correlated with the results of clinical examinations.

RESULTS

Depending on the time elapsed after RT, ORN presented with different signal intensities. The acquired images suggested that signal changes in T2-weighted images as well as the different enhancement behaviour of ORN could be dependent on the time elapsed after RT. Visualisation of the affected regions was best achieved with fat-saturated T1-weighted sequences. CT showed increased density in the affected regions corresponding to osteosclerosis. In all cases the sacroiliac joint was affected, some times bilaterally.

CONCLUSION

MRI is helpful in detecting and characterizing ORN. Changes in signal intensity, based on histopathological tissue changes could make a chronological classification possible.

Introital stenosis requiring pelvic resection and soft tissue reconstruction

BACKGROUND

Introital stenosis from both bony and soft tissue contracture is an unusual clinical problem not well addressed in the literature.

CASE

A woman with a history of pelvic irradiation at age 1 for malignancy presented with severe introital stenosis unresponsive to conservative topical and dilatational therapy. She ultimately required staged bony resection of her infantile pelvis and soft tissue reconstruction to reestablish her introital aperture to an adequate and functional size.

CONCLUSION

Introital stenosis from childhood requires a different treatment because development of the pelvis may not have been normal, and bony narrowing may exist in conjunction with soft tissue contracture. A staged multispecialty approach is recommended to treat this interesting variant of introital stenosis.

[Osteoradionecrosis after radiotherapy for gynecologic tumors]

AIM

Insufficiency fractures of the pelvis are a well known but rare and frequently misinterpreted radiation sequela. The clinical features and possible risk factors were investigated.

PATIENTS AND METHODS

71 of living 82 patients, who were treated 1986-1994 for gynecologic tumors were clinically examined. 47 patients underwent also bone scan, CT of the pelvis and 13 patients had osteodensitometry. All patients had been treated with adjuvant (n = 29) or curative intent (n = 18) by d.v. fields with 18-MV photons, with 46 Gy in 23 fractions plus brachytherapy (15-39 Gy). Median follow-up was 36 months.

RESULTS

Seven patients developed pelvic insufficiency fractures 11 months (median, minimum 2 months) after treatment. All patients complained of moderate to severe pelvic pain, which resolved after 5-28 months without specific therapy in five of seven patients. At first examination all but one bone scan showed extremely increased uptake in the os sacrum and/or iliosacral joints, correlating CT scans demonstrated small fractures and bony destruction. Four of the asymptomatic 40 patients with complete radiologic examinations had medium uptake in bone scan (CT normal). Three of four examined patients with insufficiency fractures and seven of nine patients without insufficiency fractures had osteoporosis.

CONCLUSION

In women who present with pelvic pain after radiotherapy for gynecologic tumors bony destruction and fractures may be indicative of a late radiation effect rather than osseous metastasis, even after early onset of symptoms.

Application of anisotropic diffusion to digital enhancement of portal images

We propose the use of anisotropic diffusion filtering to remedy difficulties in analysis of electronic portal images, stemming from their low contrast and high noise levels. Anisotropic diffusion is a nonlinear filter based on the numerical solution to the partial differential equation describing the process of diffusion. In this study we show that this filter is capable of greatly reducing noise in homogeneous areas of portal images while preserving the edges and contrast associated with anatomical features. We also demonstrate that the application of anisotropic diffusion leads to more consistent and reproducible visual extraction of features from portal images.

Pelvic fractures following irradiation of endometrial and vaginal cancers-a case series and review of literature

PURPOSE

To review the induction of pelvic fractures as a result of radiation therapy and to assess their management.

MATERIALS AND METHODS

The charts of patients with endometrial and vaginal cancers irradiated between 1991 and 1995 were reviewed. All patients were treated with megavoltage machines, energy ranging from cobalt to 25 MV photons.

RESULTS

We treated 336 patients, with a median follow-up duration of 28.9 months (range 0-73.3). Sixteen patients had symptomatic pelvic fractures. The 5-year actuarial incidence of symptomatic pelvic fracture was 2.1%. All patients had pain as the first symptom. The median time of onset was 11 months (range 4-46). Imaging studies of 37.5% (6/16) were initially interpreted to be recurrent malignancy. All patients were managed conservatively and nine patients showed radiological evidence of healing over a median time of 13 months (range 2-34). Six patients had specific drug treatment including provera, premarin, calcium supplements, or pamidronate. Of these, five healed. For the ten patients who did not have any specific treatment, only four showed signs of healing at the time of last follow-up. There was a trend toward earlier healing with specific drug treatment (P=0.11).

CONCLUSIONS

Fractures can easily be mistaken for metastatic lesions (37.5% in this series) which might be treated with further irradiation. Although not statistically significant, there was a trend towards early healing with drug therapy. More studies are required to generate quantitative data for dose-response relationships and to evaluate the effect of drug therapy on the healing of such fractures.

Feasibility study combining low dose rate (192)Ir brachytherapy and external beam radiotherapy aiming at delivering 80-85 Gy to prostatic adenocarcinoma

BACKGROUND

Increasing the radiation dose to prostatic adenocarcinoma has provided higher local control rates. A total of 80 Gy seem necessary to achieve this goal but patient set-up and prostate motion remain difficult problems to solve in conformal radiotherapy. Brachytherapy which overcomes these points could be an alternative way to external beam boost fields. We wanted to transpose the irradiation models largely used in cervix cancer treatment combining external beam radiotherapy and low dose rate brachytherapy.

MATERIALS AND METHODS

In 71 patients with 19.5 and 13 ng/ml mean and median PSA levels, respectively, a dose escalation from 74 to 85 Gy was performed in four groups.

RESULTS

Shifting from intraoperative placement of sources vectors (Group I) to positioning under ultrasound controls (groups II-IV), improving the implantation shape and optimizing radiation delivery to urethral bed have reduced the total dose to rectal wall under 65 Gy and to urethra under 100 Gy. Rectal/prostate dose ratio was lowered from 0.7 (Groups I-II) to 0.58 (Groups III-IV) while avoiding problems resulting from pelvic bone arch interference, prostate volume or seminal vesicles location. The mean and median follow-up periods are 28 and 18 months. In Groups III and IV 85% of patients without hormonotherapy treated with 80-85 Gy normalized PSA under 1 ng/ml within 6 months. No severe late effect has been noted for patients implanted under echographic control.

CONCLUSIONS

The method described allows to deliver 85 Gy. Longer follow-up is however needed but the levels of dose delivered are not expected to induce prohibitive side effects.

Bone marrow doses and leukaemia risk in radiotherapy of prostate cancer

BACKGROUND AND PURPOSE

As more and more patients with prostate cancer are cured and survive with only minor chronic morbidity, other potentially treatment related morbidity, in particular second cancers, becomes an urgent problem which may influence decisions on treatment strategy and treatment plan optimisation. Epidemiological data suggest a radiotherapy associated risk of AML in prostate cancer patients of approximately 0.1% in 10 years. The aim of the study was to determine the range of bone marrow doses from different treatment plans and in different patients in order to develop criteria for optimisation of treatment plans in conformal radiotherapy of prostate cancer to further minimise the small risk of secondary leukaemia.

MATERIALS AND METHODS

Doses to the pelvic bone marrow were calculated for eight different plans used in radiotherapy of prostate cancer to determine the variability of bone marrow doses in radiotherapy of prostate cancer. Computer tomography (CT) slices of the entire pelvic region of an Alderson phantom were acquired and transferred to the TPS. Critical bone marrow structures were outlined in each slice. Different treatment plans were evaluated on this phantom and dose-volume histograms (DVH) for the pelvic bone marrow were obtained. Similarly, the DVH for the bone marrow of 14 patients who received conformal radiotherapy for prostate cancer was determined.

RESULTS

Mean total bone marrow doses ranged from 3.4 to 5.6 Gy in the phantom study. Approximately 99% of the mean dose to the total bone marrow comes from the dose to bone marrow located in the pelvic bones and lumbar vertebrae. Mean bone marrow doses of 14 patients given the same conformal radiotherapy plan ranged from 3.5 to 7.7 Gy.

CONCLUSIONS

No correlation was found between the rectum normal tissue complication probability (NTCP) and the mean bone marrow dose. This means that in the process of treatment planning, exposure to both critical organs, the rectum as well as the bone marrow, should be minimised independently to arrive at the optimal treatment plan.

[Bone metastasis versus insufficiency fractures due to pelvic radiotherapy for gynecologic neoplasm]

Five cases of patients with gynecological neoplasm (four cervix carcinoma and one endometrial sarcoma) who underwent pelvic external radiotherapy and intracavitary brachytherapy in whom pathologic pelvic uptake was found in the bone scan are presented. The diagnosis was pelvic insufficiency fractures due to radiotherapy adverse effects on the skeletal system confirmed by CT and by the favorable scintigraphy and clinical outcome. Both bone metastases and insufficiency fractures must be considered in the differential diagnosis of bone pain in irradiated pelvises. The bone scintigraphy detects these insufficiency fractures early and can show a typical symmetric uptake pattern. In asymmetric lesions, the CT and clinical follow-up as well as the scintigraphic evolution of the lesions should confirm the findings of the bone scintigraphies.

Pelvic insufficiency fractures in patients with pelvic irradiation

BACKGROUND

Insufficiency fractures (IF) occur as a result of normal physiological stress on bones with deficient elastic resistance. Pelvic insufficiency fractures are a complication of osteoporosis due to postmenopausal status, high dose of corticosteroids, or local irradiation. They are important because differential diagnosis includes pelvic bone metastases. Diagnosis is based on both clinical manifestations and radiographic and scintigraphic findings.

METHODS AND MATERIALS

We examined eight patients with pelvic cancer who had previously undergone external beam radiation therapy as part of their treatment. In the follow-up, they developed insufficiency fractures, and no factor other than pelvic irradiation was present. Diagnosis was confirmed by radionuclide bone scan followed by conventional radiography and computed tomography (CT) scan.

RESULTS

The average onset of symptoms was 13.7 months after radiation therapy was completed. The initial symptom in all cases was pain. In all of the patients, the bone scan showed abnormalities. One to four increased uptake foci were observed, in the sacroiliac joint in all cases, and in the pubis in three cases. The initial diagnosis was bone metastases in five patients. CT scan showed fractures in all of the patients, in sacrum and pubis, both endostic and cortical. Treatment, consisting of nonsteroidal anti-inflammatory drugs and rest, led to symptomatic relief in all cases.

CONCLUSION

Knowledge of pelvic insufficiency fractures is essential in order to rule out metastasic disease, and thus avoid inaccurate treatment. Although radionuclide bone scan is useful in early detection of pelvic IF, definitive diagnosis is provided by CT scan.

[Radiation-induced osteonecrosis of the pelvic bones vs. bone metastases--a difficult differential diagnosis]

BACKGROUND

Since the introduction of megavoltage radiation therapy radiation osteitis has become a rare event and may be easily mistaken for bone metastases. A case of radiation osteitis is reported and diagnostic features are discussed.

CASE REPORT

A 70 year-old female patient underwent rectum resection for rectum cancer and was given standard adjuvant therapy consisting of irradiation of the tumor site and lymph nodes in the pelvis with 18 MeV photons, boxfield technique up to 50.4 Gy and chemotherapy with 5-FU. Eight months later she complained of severe lower back pain. Plain radiographs and CT revealed osteolytic lesions in the ileosacral joints and os sacrum which appeared as circumscript areas of signal loss in MRI (T1-weighted sequence). A soft tissue mass was not detected. CT-guided biopsy excluded bone metastases.

CONCLUSION

Characteristic features of radiation osteitis are spongiosa destructions initially in weight-bearing bones within the radiation field, namely the ileosacral joints, and the lack of pathologic soft tissue mass. False treatment, i.e. radiation for bone metastases, should be avoidable.

Pelvic insufficiency fractures associated with radiation atrophy: clinical recognition and diagnostic evaluation

Pelvic bone injuries are infrequent complications of radiotherapy. However, insufficiency fractures in irradiated pelvic bones may be underdetected, particularly in postmenopausal women. We describe the clinical presentation, radiologic evaluation, and course of disease in three patients with postradiation pelvic insufficiency fractures. Differential diagnosis included metastatic disease, tumor recurrence, and second malignancy. Recognition of radiographic features may prevent unnecessary, possibly morbid treatments.

Incidence of radiation-induced insufficiency fractures of the female pelvis: evaluation with MR imaging

OBJECTIVE

The purpose of this study was to assess the incidence, time of appearance, and evolution of radiation-induced insufficiency fractures of the female pelvis with MR imaging.

SUBJECTS AND METHODS

Eighteen women (nine premenopausal and nine postmenopausal) with advanced cervical carcinoma were studied prospectively with MR imaging. The examinations totaled 216 and were scheduled before radiation therapy, three times during radiation therapy, and eight times after radiation therapy. T1-weighted and short inversion time inversion recovery images were obtained. The images were evaluated by two radiologists in consensus. The criterion for fracture was edema, indicated by an area of high signal intensity on short inversion time inversion recovery images and corresponding low signal intensity on T1-weighted images. CT scans (n = 61) and bone scans (n = 58) were used to confirm each diagnosis of fracture.

RESULTS

Sixteen (89%) of 18 patients (seven premenopausal and nine postmenopausal) showed findings compatible with insufficiency fractures. Thirteen patients had more than one lesion. The first fracture was detected between 3 and 12 months after the end of radiation therapy. During the study, the fractures associated with edema subsided without treatment in 41 (79%) of 52 lesions in 15 (94%) of 16 patients. Fractures were confirmed with additional imaging in all 16 patients (CT in 14 patients and bone scanning in nine patients).

CONCLUSION

Radiation-induced insufficiency fractures were frequently seen in premenopausal and postmenopausal women within 12 months after radiation therapy. Multiple fractures developed within 24 months. Twenty-one percent of the lesions healed during the observation period of 30 months.

Incidence and possible aetiological factors in the development of pelvic insufficiency fractures following radical radiotherapy

Five patients out of a total of 183 treated with radical radiotherapy for carcinoma of cervix at The Royal Marsden Hospital from 1991 to 1994 inclusive have developed severe pelvic fractures. Two patients had rheumatoid arthritis, one of whom died as a result of the radiation induced damage. This patient developed radiological evidence of radionecrosis within 1 month of completing radiotherapy. There are very few reports in the literature of such a rapid onset. We suggest that the presence of a connective tissue disorder in a patient with other risk factors such as steroid use, old age and osteopenia should alert the clinician to the risk of radionecrosis following radical irradiation.

Pelvic insufficiency fractures after irradiation: diagnosis, management, and rehabilitation

Insufficiency fractures of the pelvis are commonly overlooked as causes of severe hip and low back pain. Predisposing factors include postmenopausal osteoporosis, corticosteroids, and local irradiation. Differential diagnosis includes metastatic disease to bone. We present the case of a 65-year-old woman who had a two-month history of low back pain and left groin pain. Her medical history included osteoporosis and endometrial cancer that was treated with radiation therapy to the pelvis 1 year prior to presentation. Despite bed rest, analgesics, and therapeutic modalities, her pain remained intractable and prevented ambulation. Plain radiographs showed no fracture. Computed tomography (CT) and magnetic resonance imaging showed fractures of the pelvis but were suggestive of malignancy. CT-guided bone biopsy was consistent with radiation osteonecrosis. After diagnosis and continued therapy, the patient progressed to ambulation with moderate discomfort. Failure to diagnose insufficiency fractures could lead to further pelvic irradiation, compromising already weakened bones and causing prolonged disability.

Total hip replacement in irradiated hips. A retrospective study of 71 cases

We retrospectively reviewed 56 patients (71 hips) treated by total replacement for severe disability after pelvic irradiation. Symptoms were associated with various radiological lesions due to irradiation, including atraumatic femoral-neck fracture, osteonecrosis of the femoral head or of the acetabulum, and radiation osteitis of the whole pelvis. From 1970 to 1982 we used standard cemented components in 49 hips and had a high rate of acetabular loosening (52%) at a mean follow-up of 69 months. This was probably due to the mechanical insufficiency of irradiated periacetabular bone. From 1983 to 1990 we routinely used acetabular reinforcement rings. The rate of aseptic acetabular loosening in 22 hips at a mean follow-up of 40 months was 19%, but there were two septic loosenings emphasising the risk of infection in these patients. When total replacement is required for an irradiated hip, we recommend reinforcement of the acetabulum using a metallic ring, but there is still an increased risk of infection and in difficult cases such as severe acetabular destruction or soft-tissue or vascular injuries, a Girdlestone procedure may be indicated.

Sacral insufficiency fractures. Spectrum of radiological features

Clinical and radiological features of 22 Chinese patients with sacral insufficiency fractures were reviewed. Twenty-one were postmenopausal women. Other risk factors were external pelvic radiotherapy (eight) and total hip replacement (two). Severe low back pain was the most common presenting complaint. Fractures initially were demonstrated by bone scintigraphy in 21 and computed tomography (CT) in seven patients. Concomitant parasymphyseal and pubic rami fractures were detected in 17 and 10 patients, respectively. Follow-up assessment by CT and bone scintigraphy in five patients showed various stages of fracture healing. Recognition of the radiological patterns of this entity is emphasized.

Radiation osteitis and insufficiency fractures after pelvic irradiation for gynecologic malignancies

Damage to the pelvic bones after radiotherapy for gynecological malignancies is uncommon with megavoltage radiotherapy. It can be misdiagnosed as bony metastases and is a diagnosis of exclusion. We report 12 women, who were treated for endometrial or cervical carcinoma who developed osteitis, femoral head or neck necrosis, or insufficiency fractures of the acetabulum, pubic symphysis or sacroiliac bones after radiotherapy. Many had multiple areas of bone damage. The prescribed external beam dose ranged from 40.0 to 61.2 Gy. All but one patient developed bony discomfort or pain as a symptom. Bony changes of the pelvic girdle appeared between 6 months and 8 years after irradiation. Radiographic studies including plain films, CT or bone scans were performed in these patients and showed correlative changes. Bone scans showed increased radionuclide uptake in affected bones. The subsequent favorable clinical course and outcome with resolution of symptoms confirmed the diagnosis of radiation osteitis. Therapy recommendations are conservative with avoidance of weight-bearing, use of analgesics and physical therapy. Femoral head necrosis/fractures required arthroplasty. Proper shielding, use of multifield technique, treatment of all fields per day, and awareness of tolerance doses are recommended.

Cervical cancer: application of MR imaging in radiation therapy

PURPOSE

To evaluate magnetic resonance (MR) imaging in the planning of radiation therapy for patients with cervical cancer.

MATERIALS AND METHODS

MR imaging was performed in 15 patients with predominantly advanced cervical carcinomas. Skin markings of the radiation ports were labeled with MR-detectable tubing and beads to assess the adequacy of port placement. Volume and extent of tumor at MR imaging were compared with those at physical and computed tomographic (CT) examinations.

RESULTS

Tumor involvement of normal structures (parametrium, vagina, endometrium) was more extensive at MR imaging than at clinical examination in six patients (40%) and at CT in five patients (33%), resulting in modification of the radiation fields in eight patients (53%). Tumor size was larger on MR images than at clinical examination in 11 patients (73%).

CONCLUSION

MR imaging can depict tumor volume and better delineate the extent of involvement than physical and CT examination. This can be useful for placement of radiation ports, especially when small boost fields are used.

Treated invasive cervical carcinoma. Utility of computed tomography in distinguishing between skeletal metastases and radiation necrosis

The bony pelvis should be carefully evaluated on computed tomography (CT) scans of the lower abdomen and pelvis performed for staging cervical cancer or for evaluating suspected recurrence. CT provides optimal imaging of the spine and pelvis, frequently providing a clinically relevant supplement to bone scan or plain film information. In a study of eight patients with skeletal metastases from cervical carcinoma and three cases of radiation osteitis, overlap existed in their imaging characteristics. Metastases were always lytic but nearby sclerotic areas from radiation were often present. Radiation osteitis may be lytic, sclerotic, or mixed, and both may avidly accumulate bone-scanning radiotracers. The absence of a soft tissue mass, slow progression, blastic elements, and sharply defined borders on CT suggest radiation necrosis. However, in some lesions within a radiation portal, biopsy or MRI may be required for final diagnosis.

Slipped capital femoral epiphysis following radiation and chemotherapy

Patients who received radiation to the proximal femoral epiphysis and chemotherapy in childhood appear to have an increased risk of subsequently developing epiphyseolysis. Every effort should be made to exclude the proximal femoral epiphysis from the radiation port whenever possible. If the epiphyseal plate is widened and irregular and the adjacent bone is sclerotic, prophylactic pinning may be indicated even in the absence of a grossly visible slip.

[Pathogenesis of skeletal radiation injuries to the proximal portion of the pelvic extremity in white rat embryos]

The mechanisms forming certain anomalies in the pelvic proximal part in the offspring of white rats subjected to x-ray radiation on the 12th and 13th days of gestation have been analysed. Serial sections of the embryos performed at various time after radiation and electron microscopic investigations have demonstrated that radiation lesions in the locomotor apparatus are of different pathogenesis. Defects in the femoral and pelvic bones, their fusion in the coxofemoral joint are anomalies resulted from destruction of some mesenchymal cells in the proximal part of the pelvic bud. Femoral dislocation, formed during gestation, is a result of disorders in coordinative muscle development, surrounding the joint and that of hypoplasia in the bursae-ligamentous apparatus (lack of head ligament, hypoplasia of the acetabular lip). Power disbalance in the muscles surrounding the joint is the main course resulting in dislocation of the femoral head.