Defining internal target volume using positron emission tomography for radiation therapy planning of moving lung tumors

Substantial disagreement exists over appropriate PET segmentation techniques for non-small cell lung cancer. Currently, no segmentation algorithm explicitly considers tumor motion in determining tumor borders. We developed an automatic PET segmentation model as a function of target volume, motion extent, and source-to-background ratio (the VMSBR model). The purpose of this work was to apply the VMSBR model and six other segmentation algorithms to a sample of lung tumors. PET and 4D CT were performed in the same imaging session for 23 patients (24 tumors) for radiation therapy planning. Internal target volumes (ITVs) were autosegmented on maximum intensity projection (MIP) of cine CT. ITVs were delineated on PET using the following methods: 15%, 35%, and 42% of maximum activity concentration, standardized uptake value (SUV) of 2.5 g/mL, 15% of mean activity concentration plus background, a linear function of mean SUV, and the VMSBR model. Predicted threshold values from each method were compared to measured optimal threshold values, and resulting volume magnitudes were compared to cine-CT-derived ITV. Correlation between predicted and measured threshold values ranged from slopes of 0.29 for the simplest single-threshold techniques to 0.90 for the VMSBR technique. R2 values ranged from 0.07 for the simplest single-threshold techniques to 0.86 for the VMSBR technique. The VMSBR segmentation technique that included volume, motion, and source-to-background ratio, produced accurate ITVs in patients when compared with cine-CT-derived ITV.

Capsular contracture of subcutaneous breast implant following hypofractionated stereotactic body radiotherapy for early stage lung cancer

BACKGROUND

Development of capsular contracture around subcutaneously implanted breast prostheses, producing poor cosmetic outcome and pain, has been reported following standard fractionated external beam radiotherapy to whole implants for breast cancer. We report capsular contracture following partial implant irradiation from hypofractionated stereotactic body radiotherapy (SBRT) for lung cancer in a 64 year-old female with augmentation mammaplasty.

METHODS

The patient had biopsy-proven, T1 non-small cell lung carcinoma, adjacent to the implant. She received 50 Gy in 4 fractions to 91% of planning target volume using a 7-field, 3D-conformal plan with 6 MV photons and daily CT-guided target localization. The implant received 9.3 Gy mean dose, 51.7 Gy maximum point dose, with V₁₀ 41%, V₂₀ 15% and V₃₀ 4%.

RESULTS

At seven months, the patient reported left breast pain requiring narcotic analgesics and demonstrated modified Baker/Palmer grade 4 capsular contracture. Breast retraction assessment measurement increased from baseline 10.4 mm to 19.8 mm.

CONCLUSIONS

This represents the first reported case of capsular contracture from partial breast implant radiation following SBRT for lung cancer. Further investigation to elucidate maximum tolerated dose of radiation given to breast implants in this setting is needed.

Target definition of moving lung tumors in positron emission tomography: correlation of optimal activity concentration thresholds with object size, motion extent, and source-to-background ratio

PURPOSE

Hardware integration of fluorodeoxyglucose positron emission tomography (PET) with computed tomography (CT) in combined PET/CT scanners has provided radiation oncologists and physicists with new possibilities for 3-D treatment simulation. The use of PET/CT simulation for target delineation of lung cancer is becoming popular and many studies concerning automatic segmentation of PET images have been performed. Several of these studies consider size and source-to-background (SBR) in their segmentation methods but neglect respiratory motion. The purpose of the current study was to develop a functional relationship between optimal activity concentration threshold, tumor volume, motion extent, and SBR using multiple regression techniques by performing an extensive series of phantom scans simulating tumors of varying sizes, SBR, and motion amplitudes. Segmented volumes on PET were compared with the "motion envelope" of the moving sphere defined on cine CT.

METHODS

A NEMA IEC thorax phantom containing six spheres (inner diameters ranging from 10 to 37 mm) was placed on a motion platform and moved sinusoidally at 0-30 mm (at 5 mm intervals) and six different SBRs (ranging from 5:1 to 50:1), producing 252 combinations of experimental parameters. PET images were acquired for 18 min and split into three 6 min acquisitions for reproducibility. The spheres (blurred on PET images due to motion) were segmented at 1% of maximum activity concentration intervals. The optimal threshold was determined by comparing deviations between the threshold volume surfaces with a reference volume surface defined on cine CT. Optimal activity concentration thresholds were normalized to background and multiple regression was used to determine the relationship between optimal threshold, volume, motion, and SBR. Standardized regression coefficients were used to assess the relative influence of each variable. The segmentation model was applied to three lung cancer patients and segmented regions of interest were compared with those segmented on cine CT.

RESULTS

The resulting model and coefficients provided a functional form that fit the phantom data with an adjusted R2 = 0.96. The most significant contributor to threshold level was SBR. Surfaces of PET-segmented volumes of three lung cancer patients were within 2 mm of the reference CT volumes on average.

CONCLUSIONS

The authors successfully developed an expression for optimal activity concentration threshold as a function of object volume, motion, and SBR.

Squamous cell carcinoma of the buccal mucosa: a retrospective analysis of 22 cases

We examined our institution's experience with 22 cases of previously untreated buccal squamous cell carcinoma via a retrospective chart review. Eleven of these patients had been treated with a combination of surgical excision and postoperative radiation therapy, 8 patients with surgical excision alone, and 3 patients with radiation therapy alone. The overall 3-year locoregional recurrence rate was 32% (n = 7). The 3-year survival rates were 82% after surgery plus radiation (9 of 11 patients), 63% after surgery alone (5 of 8), and 33% after radiation alone (1 of 3). Three-year T-category-specific survival rates were 100% for category T1 tumors (3 of 3 patients), 73% for T2 (8 of 11), 50% for T3 (3 of 6), and 50% for T4 (1 of 2). Although the small size of our study precluded any statistically significant conclusions, we believe that locoregional control and survival rates may be greater with surgical excision plus postoperative radiation than with treatment with either modality alone.

Squamous Cell Carcinoma of the Buccal Mucosa: A Retrospective Analysis of 22 Cases

We examined our institutions experience with 22 cases of previously untreated buccal squamous cell carcinoma via a retrospective chart review. Eleven of these patients had been treated with a combination of surgical excision and postoperative radiation therapy, 8 patients with surgical excision alone, and 3 patients with radiation therapy alone. The overall 3-year locoregional recurrence rate was 32% (n = 7). The 3-year survival rates were 82% after surgery plus radiation (9 of 11 patients), 63 % after surgery alone (5 of 8), and 33% after radiation alone (1 of 3). Three-year T-category-specific survival rates were 100% for category T1 tumors (3 of 3 patients), 73% for T2 (8 of 11), 50% for T3 (3 of 6), and 50% for T4 (1 of 2). Although the small size of our study precluded any statistically significant conclusions, we believe that locoregional control and survival rates may be greater with surgical excision plus postoperative radiation than with treatment with either modality alone.

Recurrent salivary gland carcinomas treated by surgery with or without intraoperative radiation therapy

BACKGROUND

The optimal treatment for patients with locally recurrent carcinomas of the salivary glands is unclear.

METHODS

Ninety-nine patients underwent salvage surgery for locally recurrent salivary gland carcinomas. Eighty-one (82%) had previously received radiation. Thirty-seven patients (37%) received intraoperative radiation therapy (IORT) to a median dose of 15 Gy (range, 12-18 Gy) at the time of salvage.

RESULTS

The 1-, 3-, and 5-year estimates of local control after salvage surgery were 88%, 75%, and 69%, respectively. A Cox proportional hazard model identified positive margins (0.01) and the omission of IORT (p = .001) as independent predictors of local failure. The 5-year overall survival was 34%. Distant metastasis was the most common site of subsequent failure, occurring in 42% of patients.

CONCLUSIONS

IORT significantly improves disease control for patients with locally recurrent carcinomas of the salivary glands. The high rate of distant metastasis emphasizes the need for effective systemic therapies.

Patterns of failure after combined-modality approaches incorporating radiotherapy for sinonasal undifferentiated carcinoma of the head and neck

PURPOSE

To report the clinical outcome of patients treated with combined-modality approaches for sinonasal undifferentiated carcinoma (SNUC) of the head and neck.

METHODS AND MATERIALS

The records of 21 patients with SNUC treated with curative intent at the University of California, San Francisco between 1990 and 2004 were analyzed. Patient age ranged from 33 to 71 years (median, 47 years). Primary tumor sites included the nasal cavity (11 patients), maxillary sinus (5 patients), and ethmoid sinus (5 patients). All patients had T3 (4 patients) or T4 (17 patients) tumors. Local-regional treatment included surgery followed by postoperative radiotherapy (PORT) with or without adjuvant chemotherapy for 17 patients; neoadjuvant chemoradiotherapy followed by surgery for 2 patients; and definitive chemoradiotherapy for 2 patients. Median follow-up among surviving patients was 58 months (range, 12-70 months).

RESULTS

The 2- and 5-year estimates of local control were 60% and 56%, respectively. There was no difference in local control according to initial treatment approach, but among the 19 patients who underwent surgery the 5-year local control rate was 74% for those with gross tumor resection, compared with 24% for those with subtotal tumor resection (p = 0.001). The 5-year rates of overall and distant metastasis-free survival were 43% and 64%, respectively. Late complications included cataracts (2 patients), lacrimal stenosis (1 patient), and sino-cutaneous fistula (1 patient).

CONCLUSION

The suboptimal outcomes suggest a need for more effective therapies. Gross total resection should be the goal of all treatments whenever possible.

Determination of Respiratory Motion for Distal Esophagus Cancer Using Four-Dimensional Computed Tomography

PURPOSE

To investigate the motion characteristics of distal esophagus cancer primary tumors using four-dimensional computed tomography (4D CT).

METHODS AND MATERIALS

Thirty-one consecutive patients treated for esophagus cancer who received respiratory-gated 4D CT imaging for treatment planning were selected. Deformable image registration was used to map the full expiratory motion gross tumor volume (GTV) to the full-inspiratory CT image, allowing quantitative assessment of each voxel's displacement. These displacements were correlated with patient tumor and respiratory characteristics.

RESULTS

The mean (SE) tidal volume was 608 (73) mL. The mean GTV volume was 64.3 (10.7) mL on expiration and 64.1 (10.7) mL on inspiration (no significant difference). The mean tumor motion in the x-direction was 0.13 (0.006) cm (average of absolute values), in the y-direction 0.23 (0.01) cm (anteriorly), and in the z-direction 0.71 (0.02) cm (inferiorly). Tumor motion correlated with tidal volume. Comparison of tumor motion above vs. below the diaphragm was significant for the average net displacement (p = 0.014), motion below the diaphragm was greater than above. From the cumulative distribution 95% of the tumors moved less than 0.80 cm radially and 1.75 cm inferiorly.

CONCLUSIONS

Primary esophagus tumor motion was evaluated with 4D CT. According to the results of this study, when 4D CT is not available, a radial margin of 0.8 cm and axial margin of +/-1.8 cm would provide tumor motion coverage for 95% of the cases in our study population.

Intrathoracic Patterns of Failure for Non–Small-Cell Lung Cancer With Positron-Emission Tomography/Computed Tomography–Defined Target Delineation

PURPOSE

Dosimetric studies suggested several advantages to defining the radiotherapy target by using positron-emission tomography (PET)/computed tomography (CT) compared with CT alone. We investigated patterns of treatment failure in patients treated to a PET-defined radiotherapy target and evaluated the effect of standardized uptake value (SUV) on recurrence after radiotherapy.

METHODS AND MATERIALS

Thirty-five patients with non-small-cell lung cancer who underwent PET/CT simulation for definitive radiotherapy were included. The PET/CT scans were obtained with patients in the treatment position with custom immobilization for use in radiation treatment planning. Nine to 11 regions of interest (ROIs) were identified for each patient, including the primary tumor and regional nodes. Maximum SUV, volume, and mean dose received were recorded for each ROI, and follow-up scans were used to evaluate for recurrence in each ROI.

RESULTS

We identified 353 ROIs from 35 patients; 5.7% of patients developed isolated out-of-field recurrences. Recursive partitioning analysis was used to divide ROIs into low, intermediate, and high risk by using volume and SUV. All low-risk ROIs with volumes less than 1.2 cm3 were recurrence free compared with 73% of intermediate-risk ROIs (volume >or=1.2 cm3; SUV <or=13.8) and 29% of high-risk ROIs (SUV > 13.8).

CONCLUSION

Limiting the target volume to predominantly PET-positive disease resulted in a low rate of isolated out-of-field recurrences. The SUV and volume were predictors of recurrence. Recursive partitioning analysis identified SUVs greater than 13.8 as the best identifier of ROIs at the greatest risk of recurrence; control rates for this subgroup did not show a dose-response relationship within the range of doses administered.

Carcinomas of the Paranasal Sinuses and Nasal Cavity Treated With Radiotherapy at a Single Institution Over Five Decades: Are We Making Improvement?

PURPOSE

To compare clinical outcomes of patients with carcinomas of the paranasal sinuses and nasal cavity according to decade of radiation treatment.

METHODS AND MATERIALS

Between 1960 and 2005, 127 patients with sinonasal carcinoma underwent radiotherapy with planning and delivery techniques available at the time of treatment. Fifty-nine patients were treated by conventional radiotherapy; 45 patients by three-dimensional conformal radiotherapy; and 23 patients by intensity-modulated radiotherapy. Eighty-two patients (65%) were treated with radiotherapy after gross total tumor resection. Nineteen patients (15%) received chemotherapy. The most common histology was squamous cell carcinoma (83 patients).

RESULTS

The 5-year estimates of overall survival, local control, and disease-free survival for the entire patient population were 52%, 62%, and 54%, respectively. There were no significant differences in any of these endpoints with respect to decade of treatment or radiotherapy technique (p > 0.05, for all). The 5-year overall survival rate for patients treated in the 1960s, 1970s, 1980s, 1990s, and 2000s was 46%, 56%, 51%, 53%, and 49%, respectively (p = 0.23). The observed incidence of severe (Grade 3 or 4) late toxicity was 53%, 45%, 39%, 28%, and 16% among patients treated in the 1960s, 1970s, 1980s, 1990s, and 2000s, respectively (p = 0.01).

CONCLUSION

Although we did not detect improvements in disease control or overall survival for patients treated over time, the incidence of complications has significantly declined, thereby resulting in an improved therapeutic ratio for patients with carcinomas of the paranasal sinuses and nasal cavity.

Evaluation of respiratory-induced target motion for esophageal tumors at the gastroesophageal junction

PURPOSE

To quantify the internal motion margin requirements for radiotherapy of tumors near the gastroesophageal junction (GEJ).

METHODS AND MATERIALS

Four-dimensional computed tomography (4DCT) scans were obtained for 25 patients with primary tumors located near the GEJ. The gross tumor volume (GTV) was manually contoured on the exhale-phase image from the 4DCT image set. A deformable image registration method was used to automatically propagate the contours to other phases of the 4DCT images. To quantify target motion, we measured the displacement of the GTV centroid and the variations in the target boundary and volume. Internal margins were calculated in the lateral (RL), anterior-posterior (AP), and superior-inferior (SI) directions.

RESULTS

The mean+/-standard deviation peak-to-peak GTV centroid motion was 0.39+/-0.27cm (range, 0.04-1.09cm) in the RL, 0.38+/-0.23cm (range, 0.10-0.94cm) in the AP, and 0.87+/-0.47cm (range, 0.43-2.63cm) in the SI directions, respectively. On average, the internal target volume was 72% (range, 9-172%) larger than the GTV defined on a single-phase CT image. Variations in tumor boundaries due to tissue motion and deformation suggested asymmetric margins: 1.0cm left [toward the stomach], 0.8cm right, 1.1cm anterior, 0.6cm posterior, 1.0cm superior (toward the distal esophagus), and 1.6cm inferior (toward the stomach).

CONCLUSION

Because tumors near the GEJ are subject to a marked but asymmetric amount of respiratory-induced intrafractional tumor motion, the use of asymmetric internal margins may be beneficial.

Patterns of nodal relapse after surgery and postoperative radiation therapy for carcinomas of the major and minor salivary glands: What is the role of elective neck irradiation?

PURPOSE

To evaluate the incidence of nodal relapses from carcinomas of the salivary glands among patients with clinically negative necks in an attempt to determine the potential utility of elective neck irradiation (ENI).

METHODS AND MATERIALS

Between 1960 and 2004, 251 patients with clinically N0 carcinomas of the salivary glands were treated with surgery and postoperative radiation therapy. None of the patients had undergone previous neck dissection. Histology was: adenoid cystic (84 patients), mucoepidermoid (60 patients), adenocarcinoma (58 patients), acinic cell (21 patients), undifferentiated (11 patients), carcinoma ex pleomorphic adenoma (7 patients), squamous cell (7 patients), and salivary duct carcinoma (3 patients); 131 patients (52%) had ENI. Median follow-up was 62 months (range, 3-267 months).

RESULTS

The 5- and 10-year actuarial estimates of nodal relapse were 11% and 13%, respectively. The 10-year actuarial rates of nodal failure were 7%, 5%, 12%, and 16%, for patients with T1, T2, T3, and T4 disease, respectively (p = 0.11). The use of ENI reduced the 10-year nodal failure rate from 26% to 0% (p = 0.0001). The highest crude rates of nodal relapse among those treated without ENI were found in patients with squamous cell carcinoma (67%), undifferentiated carcinoma (50%), adenocarcinoma (34%), and mucoepidermoid carcinoma (29%). There were no nodal failures observed among patients with adenoid cystic or acinic cell histology.

CONCLUSION

ENI effectively prevents nodal relapses and should be used for select patients at high risk for regional failure.

Intensity-modulated radiation therapy for malignancies of the nasal cavity and paranasal sinuses

PURPOSE

To report the clinical outcome of patients treated with intensity-modulated radiation therapy (IMRT) for malignancies of the nasal cavity and paranasal sinuses.

METHODS AND MATERIALS

Between 1998 and 2004, 36 patients with malignancies of the sinonasal region were treated with IMRT. Thirty-two patients (89%) were treated in the postoperative setting after gross total resection. Treatment plans were designed to provide a dose of 70 Gy to 95% or more of the gross tumor volume (GTV) and 60 Gy to 95% or more of the clinical tumor volume (CTV) while sparing neighboring critical structures including the optic chiasm, optic nerves, eyes, and brainstem. The primary sites were: 13 ethmoid sinus, 10 maxillary sinus, 7 nasal cavity, and 6 other. Histology was: 12 squamous cell, 7 esthesioneuroblastoma, 5 adenoid cystic, 5 undifferentiated, 5 adenocarcinoma, and 2 other. Median follow-up was 51 months among surviving patients (range, 9-82 months).

RESULTS

The 2-year and 5-year estimates of local control were 62% and 58%, respectively. One patient developed isolated distant metastasis, and none developed isolated regional failure. The 5-year rates of disease-free and overall survival were 55% and 45%, respectively. The incidence of ocular toxicity was minimal with no patients reporting decreased vision. Late complications included xerophthalmia (1 patient), lacrimal stenosis (1 patient), and cataract (1 patient).

CONCLUSION

Although IMRT for malignancies of the sinonasal region does not appear to lead to significant improvements in disease control, the low incidence of complications is encouraging.

Local-regional recurrence after surgery without postoperative irradiation for carcinomas of the major salivary glands: implications for adjuvant therapy

PURPOSE

To determine factors predictive of local-regional recurrence (LRR) after surgery alone for carcinomas of the major salivary glands in an attempt to evaluate the potential role of postoperative radiation therapy.

METHODS AND MATERIALS

Between 1960 and 2004, 207 patients with carcinomas of the major salivary glands were treated with definitive surgery without postoperative radiation therapy. Histology was: 67 mucoepidermoid (32%), 50 adenoid cystic (24%), 34 acinic cell (16%), 23 malignant mixed (11%), 16 adenocarcinoma (8%), 6 oncocytic (3%), 6 myoepithelial (3%), and 5 other (2%). Distribution of pathologic T-stage was: 54 T1 (26%), 83 T2 (40%), 46 T3 (22%), and 24 T4 (12%). Sixty patients (29%) had microscopically positive margins. Median follow-up was 6.1 years (range, 0.5-18.7 years).

RESULTS

The 5-year and 10-year estimates of local-regional control were 86% and 74%, respectively. A Cox proportional hazard model identified pathologic lymph node metastasis (hazard ratio [HR], 4.8; p = 0.001), high histologic grade (HR, 4.2; p = 0.003), positive margins (HR, 2.6; p = 0.03), and T3-4 disease (HR, 2.0; p = 0.04) as independent predictors of LRR. The presence of any one of these factors was associated with 10-year local-regional control rates of 37% to 63%.

CONCLUSION

Lymph node metastasis, high tumor grade, positive margins, and T3-4 stage predict for significant rates of LRR after surgery for carcinomas of the major salivary glands. Postoperative radiation therapy should be considered for patients with these disease characteristics.

Intraoperative radiation therapy for recurrent head-and-neck cancer: the UCSF experience

PURPOSE

To review a single-institutional experience with the use of intraoperative radiation therapy (IORT) for recurrent head-and-neck cancer.

METHODS AND MATERIALS

Between 1991 and 2004, 137 patients were treated with gross total resection and IORT for recurrence or persistence of locoregional cancer of the head and neck. One hundred and thirteen patients (83%) had previously received external beam radiation as a component of definitive therapy. Ninety-four patients (69%) had squamous cell histology. Final surgical margins were microscopically positive in 56 patients (41%). IORT was delivered using either a modified linear accelerator or a mobile electron unit and was administered as a single fraction to a median dose of 15 Gy (range, 10-18 Gy). Median follow-up among surviving patients was 41 months (range, 3-122 months).

RESULTS

The 1-year, 2-year, and 3-year estimates of in-field control after salvage surgery and IORT were 70%, 64%, and 61%, respectively. Positive margins at the time of IORT predicted for in-field failure (p = 0.001). The 3-year rates of locoregional control, distant metastasis-free survival, and overall survival were 51%, 46%, and 36%, respectively. There were no perioperative fatalities. Complications included wound infection (4 patients), orocutaneous fistula (2 patients), flap necrosis (1 patient), trismus (1 patient), and neuropathy (1 patient).

CONCLUSIONS

Intraoperative RT results in effective disease control with acceptable toxicity and should be considered for selected patients with recurrent or persistent cancers of the head and neck.

Recurrent pleomorphic adenoma of the parotid gland: Long-term outcome of patients treated with radiation therapy

PURPOSE

To evaluate the role of radiation therapy in the management of recurrent pleomorphic adenoma of the parotid gland.

METHODS AND MATERIALS

Between 1960 and 2004, 34 patients were treated with postoperative radiation therapy for recurrent pleomorphic adenoma of the parotid gland to a median dose of 5000 cGy (range, 4,500-6,000 cGy). Median age was 48 years (range, 24-72 years). Gross total resection at the time of surgery before radiation was achieved in 30 patients (88%), and histologic analysis demonstrated multifocal disease in 16 patients (47%). Radiation was delivered for a first, second, third, fourth, fifth, and sixth local recurrence in 24%, 21%, 24%, 24%, 6%, and 3% of patients, respectively.

RESULTS

With a median follow-up of 17.4 years (range, 2.3-28.9 years), 2 patients had local recurrences at a median of 3.4 years after completion of radiation. The 20-year actuarial local control rate was 94%. One patient developed a second malignancy at approximately 14 years after completion of therapy.

CONCLUSION

The use of postoperative radiation therapy leads to excellent long-term local control for the treatment of recurrent pleomorphic adenoma with acceptable late toxicity. Although the incidence of second malignancy was low in this population, continued follow-up is warranted.

The role of postoperative radiation therapy in carcinoma ex pleomorphic adenoma of the parotid gland

PURPOSE

To evaluate the impact of postoperative radiation therapy on the clinical course of patients with carcinoma ex pleomorphic adenoma of the parotid gland.

METHODS AND MATERIALS

Between 1960 and 2004, 63 patients were treated with definitive surgery for carcinoma ex pleomorphic adenoma of the parotid gland. Forty patients (63%) received postoperative radiation therapy to a median dose of 60 Gy (range, 45-71 Gy). Adenocarcinoma (29 patients), salivary duct carcinoma (16 patients), and adenoid cystic carcinoma (9 patients) were the most common malignant subtypes. Pathologic T -stage was: 16% T1, 33% T2, 32% T3, and 19% T4. Twenty-one patients (33%) had microscopically positive margins and 39 (62%) had perineural invasion. Median follow-up was 50 months (range, 2-96 months).

RESULTS

The use of postoperative therapy significantly improved 5-year local control from 49% to 75% (p = 0.005) and was associated with an improvement in survival among patients without evidence of cervical lymph node metastasis (p = 0.01). A Cox proportional hazard model identified pathologic involvement of cervical lymph nodes as an independent predictor of overall survival. Overall survival was 16% for patients with pathologic N-positive disease compared with 67% for those whose lymph node status was negative or unknown (p = 0.001).

CONCLUSION

Surgery followed by postoperative radiation should be considered the standard of care for patients with carcinoma ex pleomorphic adenoma.

Megavoltage cone-beam CT: system description and clinical applications

In this article, we describe a clinical mega-voltage cone-beam computed tomography (MV CBCT) system, present the image acquisition and patient setup procedure, discuss the positioning accuracy and image quality, and illustrate its potential use for image-guided radiation therapy (IGRT) through selected clinical examples. The MV CBCT system consists of a standard linear accelerator equipped with an amorphous-silicon flat panel electronic portal-imaging device adapted for mega-electron volt (MeV) photons. An integrated computer workspace provides automated acquisition of projection images, image reconstruction, CT to CBCT image registration, and couch shift calculation. The system demonstrates submillimeter localization precision and sufficient soft-tissue resolution to visualize structures such as the prostate. In our clinic, we have used the MV CBCT system to detect nonrigid spinal cord distortions, monitor tumor growth and shrinkage, and locate and position stationary tumors in the lung. MV CBCT has also greatly improved the delineation of structures in CT images that suffer from metal artifacts. MV CBCT has undergone significant development in the last few years. Current image quality has already proven sufficient for many IGRT applications. Moreover, we expect the range of clinical applications for MV CBCT to grow as imaging technology continues to improve.

Long-term outcome of patients treated by radiation therapy alone for salivary gland carcinomas

PURPOSE

To review a single-institution experience with the management of salivary gland cancers treated by radiation alone.

METHODS AND MATERIALS

Between 1960 and 2004, 45 patients with newly diagnosed salivary gland carcinomas were treated with definitive radiation to a median dose of 66 Gy (range, 57-74 Gy). Distribution of T-stage was: 24% T1, 18% T2, 31% T3, and 27% T4. Histology was: 14 mucoepidermoid (31%), 10 adenocarcinoma (22%), 8 adenoid cystic (18%), 4 undifferentiated (9%), 4 acinic (9%), 2 malignant mixed (4%), 2 squamous (4%), and 1 salivary duct carcinoma (2%). No patient had clinical or pathologic evidence of lymph node disease. Median follow-up was 101 months (range, 3-285 months).

RESULTS

The 5-year and 10-year rate estimates of local control were 70% and 57%, respectively. A Cox proportional hazard model identified T3-4 disease (p = 0.004) and radiation dose lower than 66 Gy (p = 0.001) as independent predictors of local recurrence. The 10-year overall survival and distant metastasis-free rates were 46% and 67%, respectively.

CONCLUSION

Radiation therapy alone is a reasonable alternative to surgery in the definitive management of salivary gland cancers and results in long-term survival in a significant proportion of patients. Radiation dose in excess of 66 Gy is recommended.

Dose-guided radiation therapy with megavoltage cone-beam CT

Recent advances in fractionated external beam radiation therapy have increased our ability to deliver radiation doses that conform more tightly to the tumour volume. The steeper dose gradients delivered in these treatments make it increasingly important to set precisely the positions of the patient and the internal organs. For this reason, considerable research now focuses on methods using three-dimensional images of the patient on the treatment table to adapt either the patient position or the treatment plan, to account for variable organ locations. In this article, we briefly review the different adaptive methods being explored and discuss a proposed dose-guided radiation therapy strategy that adapts the treatment for future fractions to compensate for dosimetric errors from past fractions. The main component of this strategy is a procedure to reconstruct the dose delivered to the patient based on treatment-time portal images and pre-treatment megavoltage cone-beam computed tomography (MV CBCT) images of the patient. We describe the work to date performed to develop our dose reconstruction procedure, including the implementation of a MV CBCT system for clinical use, experiments performed to calibrate MV CBCT for electron density and to use the calibrated MV CBCT for dose calculations, and the dosimetric calibration of the portal imager. We also present an example of a reconstructed patient dose using a preliminary reconstruction program and discuss the technical challenges that remain to full implementation of dose reconstruction and dose-guided therapy.

Adenoid cystic carcinoma of the head and neck treated by surgery with or without postoperative radiation therapy: Prognostic features of recurrence

PURPOSE

This study sought to review a single-institution experience with the management of adenoid cystic carcinoma of the head and neck.

METHODS AND MATERIALS

Between 1960 and 2004, 140 patients with adenoid cystic carcinoma of the head and neck were treated with definitive surgery. Ninety patients (64%) received postoperative radiation to a median dose of 64 Gy (range, 54-71 Gy). Distribution of T stage was: 26% T1, 28% T2, 20% T3, and 26% T4. Seventy-eight patients (56%) had microscopically positive margins. Median follow-up was 66 months (range, 7-267 months).

RESULTS

The 5- and 10-year rate estimates of local control were 88% and 77%, respectively. A Cox proportional hazards model identified T4 disease (p = 0.0001), perineural invasion (p = 0.008), omission of postoperative radiation (p = 0.007), and major nerve involvement (p = 0.02) as independent predictors of local recurrence. Radiation dose lower than 60 Gy (p = 0.0004), T4 disease (p = 0.005), and major nerve involvement (p = 0.02) were predictors of local recurrence among those treated with surgery and postoperative radiation. The 10-year overall survival and distant metastasis-free survival were 64% and 66%, respectively.

CONCLUSION

Combined-modality therapy with surgery followed by radiation to doses in excess of 60 Gy should be considered the standard of care for adenoid cystic carcinoma of the head and neck.

Phase III Trial of an Emulsion Containing Trolamine for the Prevention of Radiation Dermatitis in Patients With Advanced Squamous Cell Carcinoma of the Head and Neck: Results of Radiation Therapy Oncology Group Trial 99-13

Purpose

This multicentered phase III trial was designed to compare an emulsion containing trolamine against the usual supportive care within each participating institution for patients with head and neck cancer undergoing radiation therapy.

Patients and Methods

Patients with biopsy-proven squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, or larynx were randomly assigned to one of the following treatments: prophylactic trolamine emulsion, interventional trolamine emulsion, or declared institutional preference. The primary outcome was the reduction in grade 2 or higher skin toxicity, as per National Cancer Institute Common Toxicity Criteria version 2.0. Secondary outcomes included patient-reported quality of life (QOL).

Results

From October 2000 to April 2002, 547 patients from 51 institutions were entered onto the trial. The average age was 59 years. Patients were predominately male (79%) and most continued to use tobacco products (52%). The rates of grade 2 or higher radiation dermatitis were 79%, 77%, and 79% in the prophylactic, interventional, and institutional preference arms of the study, respectively. No significant differences in QOL were found.

Conclusion

The results of this trial demonstrate no advantage for the use of trolamine in reducing the incidence of grade 2 or higher radiation dermatitis or improving patient-reported QOL. The use of 15 different local standards of care highlights the need to continue research that will result in evidence-based recommendations to reduce the burden of radiation dermatitis.

Repeat CT imaging and replanning during the course of IMRT for head-and-neck cancer

PURPOSE

Many patients with head-and-neck (H&N) cancer have tumor shrinkage and/or weight loss during the course of radiotherapy. We conducted this retrospective study to determine the dosimetric effects of repeat computed tomography (CT) imaging and replanning during the course of intensity-modulated radiotherapy (IMRT) on both normal tissues and target volumes.

METHODS AND MATERIALS

A retrospective chart review identified 13 patients with H&N cancer treated with IMRT who had repeat CT imaging and replanning during the course of radiotherapy. The first IMRT plan for each patient was generated based on the original planning CT scan acquired before the start of treatment. Because of tumor shrinkage or weight loss during radiotherapy, a second CT scan was acquired, and a new plan was generated and used to complete the course of IMRT. CT-CT fusion was used to correct patient positioning differences between the scans. By using a commercial inverse IMRT planning system, a hybrid IMRT plan was generated for each patient by applying the beam configurations of the first IMRT plan (including the intensity profile of each beam) to the anatomy of the second CT scan. The dose-volume histograms of the actual and hybrid IMRT plans were compared using analysis of variance methods for repeated measures.

RESULTS

All patients had locally advanced, nonmetastatic Stage III or IV disease, including 6 nasopharynx, 6 oropharynx, and 1 unknown primary site. All patients were treated with concurrent platinum-based chemotherapy. When replanning vs. not replanning was compared, the hybrid IMRT plans (without replanning) demonstrated reduced doses to target volumes and increased doses to critical structures. The doses to 95% (D95) of the planning target volumes of the gross tumor volume (PTVGTV) and the clinical target volume (PTVCTV) were reduced in 92% of patients, by 0.8-6.3 Gy (p=0.02) and 0.2-7.4 Gy (p=0.003), respectively. The maximum dose (Dmax) to the spinal cord increased in all patients (range, 0.2-15.4 Gy; p=0.003) and the brainstem Dmax increased in 85% of patients without replanning (range, 0.6-8.1 Gy; p=0.007).

CONCLUSIONS

Repeat CT imaging and replanning during the course of IMRT for selected patients with H&N cancer is essential to identify dosimetric changes and to ensure adequate doses to target volumes and safe doses to normal tissues. Future prospective studies with larger sample sizes will help to determine criteria for repeat CT imaging and IMRT replanning for H&N cancer patients undergoing radiotherapy.

Management of Cervical Metastases in Advanced Squamous Cell Carcinoma of the Tonsillar Fossa Following Radiotherapy

OBJECTIVE

To assess the value of planned neck dissection in patients with a complete response to definitive radiotherapy for squamous cell carcinoma of the tonsillar fossa with advanced nodal disease.

DESIGN

Case series.

SETTING

Academic tertiary care medical center.

PATIENTS

A consecutive series of 36 patients with squamous cell carcinoma of the tonsillar fossa with N2 or N3 nodal disease treated with primary radiation therapy with or without concurrent chemotherapy between January 1, 1992, and April 1, 2003, at the University of California, San Francisco, Comprehensive Cancer Center. Patients treated with primary surgery, those treated with palliative intent, or those with preexisting malignancies were excluded.

MAIN OUTCOME MEASURES

Regional control and overall survival.

RESULTS

Of the study group, 15 patients (42%) achieved a complete response, 17 (47%) achieved a partial response, and 1 (3%) was a nonresponder. The response in 3 patients (8%) could not be assessed. Of the 15 patients with a complete response, only 2 (13%) later developed regional recurrences, 1 of which was an isolated recurrence in the neck. Regional control and overall survival at 3 years were 78% and 48%, respectively.

CONCLUSIONS

The rate of regional recurrence after a complete response to radiation therapy with or without concurrent chemotherapy for tonsillar squamous cell carcinoma with advanced cervical metastases is low. Our results support close surveillance of the neck in those who have achieved a complete response after radiation therapy with or without chemotherapy.

Advances in radiation therapy: conventional to 3D, to IMRT, to 4D, and beyond

Modern advances in computers have fueled parallel advances in imaging technologies. The improvements in imaging have in turn allowed a higher level of complexity to be incorporated into radiotherapy treatment planning systems. As a result of these changes, the delivery of radiotherapy evolved from therapy designed based primarily on plain (two dimensional) x-ray images and hand calculations to three-dimensional x-ray based images incorporating increasingly complex computer algorithms. More recently, biologic variables based on differences between tumor metabolism, tumor antigens, and normal tissues have been incorporated into the treatment process. In addition, greater awareness of the challenges to the accuracy of the treatment planning process, such as problems with set-error and organ movement, have begun to be systematically addressed, ushering in an era of so-called Four-Dimensional Radiotherapy. This review article discusses how these advances have changed the way the most common neoplasms are treated now and will be treated in the near future.