- Email: [email protected]
What is the Microscopic Tumor Extent beyond Clinically Delineated Gross Tumor Boundary in Nonmelanoma Skin Cancers?
Proceedings of the 47th Annual ASTRO Meeting
Pinnacle planning software. The original contoured gross tumor volume (GTV) was used to create a conformal and an IMRT plan for each patient. A clinical target volume (CTV) appropriate to the management of STS was contoured around the GTV and utilized for all 3 plans. The future surgical flaps were created virtually through contouring with the assistance of the treating surgeon and regarded as an organ at risk (OAR). In areas where the flaps and CTV overlapped, the CTV was given priority. Dose constraints for the flaps were prioritized at 30 Gy, 40 Gy was used for the bone and the prescribed dose for the CTV was 50 Gy. CTV and OAR dose-volume histograms were calculated and the plans compared for conformality ([total volumeⱖ desired dose] / [target volume ⱖdesired dose]), target coverage ([target volumeⱖ desired dose] / total target volume), and dose sparing. Results: Results are summarized in Table 1. There was no difference in the mean bone or CTV dose between the 3 plans, but there was a significant difference in mean dose to flaps for all 3 plans (p⫽0.0001). For mean percentage of flap treated to 30 Gy or more, there was no significant difference between the original and conformal plans, but there was between the original and IMRT plans (p⫽0.0005) and the conformal and IMRT plans (p⫽0.0002). For mean percentage of bone treated to 40 Gy or more there was again no difference between the original and conformal plans, but there was between the original and IMRT (p⫽0.0003) and the conformal and IMRT (p⫽0.001). There was no difference in mean target coverage between all three plans. There was an obvious trend to improved target conformality when employing IMRT as compared to the original and conformal plans. Conclusions: In a retrospective review, preoperative IMRT substantially lowers the dose to the planned region encompassing the future surgical flaps and spares a greater percentage of the volume of this entity without compromising target (tumor) coverage. Its effect on decreasing acute wound healing complications needs to be verified in the clinical setting and a prospective trial is about to commence at our institution. Table 1: Plan comparison metrics
Values in parentheses represent the range.
81
What is the Microscopic Tumor Extent beyond Clinically Delineated Gross Tumor Boundary in Nonmelanoma Skin Cancers?
R. Choo,1,2 T. Woo,2 E. Barnes,2 D. Assaad,2 O. Antonyshyn,2 D. Mckenzie,2 J. Fialkov,2 D. Breen,2 A. Mamedov2 Radiation Oncology, Mayo Clinic, Rochester, MN, 2Radiation Oncology, Toronto Sunnybrook Regional Cancer Centre, University of Toronto, Toronto, ON, Canada
1
Purpose/Objective: To quantify the microscopic tumor extension beyond clinically delineated gross tumor boundary in nonmelanoma skin cancers. Little information exists in literature for this subject. When radiotherapy (RT) is applied as a primary, definitive therapy for nonmelanoma skin cancers, the accurate assessment of microscopic tumor extent is a critical element for the success of RT. Tissue volume containing the sub-clinical microscopic tumor extent is equivalent to clinical target volume in radiotherapy setting. Materials/Methods: A prospective, single arm, study. Preoperatively a radiation oncologist outlined the boundary of a gross lesion, and drew 5-mm incremental marks peripherally in 4 directions from the delineated border. Under local anesthesia, the lesion was excised, and resection margins were assessed microscopically by frozen section. Once resection margins were clear, the microscopic tumor extent was calculated using the pre-surgical incremental markings as references. A potential relationship between the distance of microscopic tumor extension and other variables was analyzed. Results: A total of 71 lesions in 64 consecutive patients, selected for surgical excision with frozen-section assisted assessment of resection margins, were accrued between Nov. 2003 and May 2004. 38, 19, and 14 cases were sclerosing basal cell carcinoma (BCC), other type BCC, and squamous cell carcinoma (SCC), respectively. 31 cases were recurrent cancer with various previous treatments. The average distance of maximal microscopic tumor extension peripherally
S49
S50
I. J. Radiation Oncology
● Biology ● Physics
Volume 63, Number 2, Supplement, 2005
beyond a gross lesion was 5.2 mm (range:1–15) for the entire 71 lesions. It was 5.0 mm (range:1–13) for sclerosing BCC, 5.3 mm (range:2–15) for other type BCC, and 5.7 mm (range:2–10) for SCC. The figure shows the probability of clear resection margin vs. the distance beyond clinically delineated gross tumor. In only 62% of cases did 5 mm margin around the clinically delineated tumor border adequately cover the microscopic peripheral tumor extent. A margin of 10 mm was required to provide a 95% chance of obtaining clear resection margins. The microscopic tumor extent was positively correlated with the size of gross lesion (Pearson r ⫽ 0.47, p ⬍ 0.0001), but not with other variables (histology type, location of lesion, and presence/absence of previous treatment history). Conclusions: The peripheral distance of microscopic tumor extension beyond a gross tumor in nonmelanoma skin cancer was variable with a mean of 5.2 mm. The larger the size of a lesion, the greater the extent of microscopic tumor extension. Such information is critical for the proper radiation planning of skin cancer.
82
Sustained Remission Following Radiation Treatment for High-Risk Pigmented Villonodular Synovitis
B. O’Sullivan,1,2 A. Griffin,4 J. Wunder,4,2 P. Marks,7,2 C. Catton,1,2 P. Ferguson,4,2 P. Chung,1,2 R. Kandel,5,2 L. White,6,2 R. Bell3,2 1 Department of Radiation Oncology, Princess Margaret Hospital, Toronto, ON, Canada, 2University of Toronto, Toronto, ON, Canada, 3Department of Surgical Oncology, Princess Margaret Hospital, Toronto, ON, Canada, 4 Division of Orthopaedic Surgery, Mount Sinai Hospital, Toronto, ON, Canada, 5Department of Pathology, Mount Sinai Hospital, Toronto, ON, Canada, 6Department of Medical Imaging, Mount Sinai Hospital, Toronto, ON, Canada, 7 Department of Orthopaedic Surgery, Orthopaedic and Arthritic Institute, Toronto, ON, Canada
Purpose/Objective: Pigmented villonodular synovitis (PVNS) is a rare proliferative process originating from synovial membranes. Usually benign, it may be destructive, resulting in major symptoms and loss of function leading to amputation rarely. There is a paucity of outcome data following radiotherapy in high risk cases. Our purpose was to update a prior experience with extended follow-up and almost three times greater accrual of cases at high risk for recurrence with functional loss including instances where amputation was the sole alternative for symptomatic disease. Materials/Methods: The records of all patients (41 cases) who received radiotherapy for PVNS between 1972 and 2003 were reviewed retrospectively and, since 1986, prospectively. Eligibility included at least one year of follow-up following radiotherapy. Local control was defined as absence of clinical or imaging evidence of disease following treatment in either patients without overt disease at the time of radiotherapy, or in patients with stable disease on serial cross-sectional imaging of gross disease for at least one year following treatment. Results: All cases had pathologic confirmation of diagnosis at our center. 18 had primary and 23 recurrent disease (with a mean of 2 prior surgical procedures). 36 had origin from a joint (most commonly the knee in 37%) and 5 arose in periarticular tendon sheath. All but 1 had both intra- and extraarticular disease and, without exception, the poorer prognosis diffuse subtype of the disease. The majority had one or more additional risk factors including skin, bone, tendon, neurovascular, or muscle group extension and 17 of these lesion exceeded 10 cm in maximum dimension. 21 had gross residual disease at the time of radiotherapy. The mean radiotherapy dose was 38 Gy (range 28 Gy to 50 Gy), the majority receiving 35 Gy in 14 fractions. One patient had the malignant variant of PVNS and is the only patient with clear resection margins consistent with oncologic principles for malignant sarcomas. With a mean follow-up time of 77 months (range 13–337 months), only one patient has shown active disease by the criteria described. Two additional cases (both tendon sheath lesions of the wrist/hand) underwent subsequent biopsies of a palpable asymptomatic stable lesion (⬍1 cm in size). In one this took place 9 years following radiotherapy and he remained without treatment or progression 17 years later; the second had a biopsy 16 years following treatment, had no additional therapy and was well without progression 3 years later. No patient required amputation, and none had evidence of serious radiotherapy complications. Only one patient has developed a second malignancy, specifically a brain tumor but the site of PVNS was the ankle. Conclusions: Moderate dose radiotherapy is a very effective treatment in PVNS and permits local control and avoidance of amputation in very advanced and typically recurrent cases. When treatment is indicated we currently recommend gross total removal of PVNS followed by moderate dose radiotherapy for residual disease where salvage of subsequent recurrence may compromise function. Alternatively control of gross disease can also be expected following radiotherapy.
Pinnacle planning software. The original contoured gross tumor volume (GTV) was used to create a conformal and an IMRT plan for each patient. A clinical target volume (CTV) appropriate to the management of STS was contoured around the GTV and utilized for all 3 plans. The future surgical flaps were created virtually through contouring with the assistance of the treating surgeon and regarded as an organ at risk (OAR). In areas where the flaps and CTV overlapped, the CTV was given priority. Dose constraints for the flaps were prioritized at 30 Gy, 40 Gy was used for the bone and the prescribed dose for the CTV was 50 Gy. CTV and OAR dose-volume histograms were calculated and the plans compared for conformality ([total volumeⱖ desired dose] / [target volume ⱖdesired dose]), target coverage ([target volumeⱖ desired dose] / total target volume), and dose sparing. Results: Results are summarized in Table 1. There was no difference in the mean bone or CTV dose between the 3 plans, but there was a significant difference in mean dose to flaps for all 3 plans (p⫽0.0001). For mean percentage of flap treated to 30 Gy or more, there was no significant difference between the original and conformal plans, but there was between the original and IMRT plans (p⫽0.0005) and the conformal and IMRT plans (p⫽0.0002). For mean percentage of bone treated to 40 Gy or more there was again no difference between the original and conformal plans, but there was between the original and IMRT (p⫽0.0003) and the conformal and IMRT (p⫽0.001). There was no difference in mean target coverage between all three plans. There was an obvious trend to improved target conformality when employing IMRT as compared to the original and conformal plans. Conclusions: In a retrospective review, preoperative IMRT substantially lowers the dose to the planned region encompassing the future surgical flaps and spares a greater percentage of the volume of this entity without compromising target (tumor) coverage. Its effect on decreasing acute wound healing complications needs to be verified in the clinical setting and a prospective trial is about to commence at our institution. Table 1: Plan comparison metrics
Values in parentheses represent the range.
81
What is the Microscopic Tumor Extent beyond Clinically Delineated Gross Tumor Boundary in Nonmelanoma Skin Cancers?
R. Choo,1,2 T. Woo,2 E. Barnes,2 D. Assaad,2 O. Antonyshyn,2 D. Mckenzie,2 J. Fialkov,2 D. Breen,2 A. Mamedov2 Radiation Oncology, Mayo Clinic, Rochester, MN, 2Radiation Oncology, Toronto Sunnybrook Regional Cancer Centre, University of Toronto, Toronto, ON, Canada
1
Purpose/Objective: To quantify the microscopic tumor extension beyond clinically delineated gross tumor boundary in nonmelanoma skin cancers. Little information exists in literature for this subject. When radiotherapy (RT) is applied as a primary, definitive therapy for nonmelanoma skin cancers, the accurate assessment of microscopic tumor extent is a critical element for the success of RT. Tissue volume containing the sub-clinical microscopic tumor extent is equivalent to clinical target volume in radiotherapy setting. Materials/Methods: A prospective, single arm, study. Preoperatively a radiation oncologist outlined the boundary of a gross lesion, and drew 5-mm incremental marks peripherally in 4 directions from the delineated border. Under local anesthesia, the lesion was excised, and resection margins were assessed microscopically by frozen section. Once resection margins were clear, the microscopic tumor extent was calculated using the pre-surgical incremental markings as references. A potential relationship between the distance of microscopic tumor extension and other variables was analyzed. Results: A total of 71 lesions in 64 consecutive patients, selected for surgical excision with frozen-section assisted assessment of resection margins, were accrued between Nov. 2003 and May 2004. 38, 19, and 14 cases were sclerosing basal cell carcinoma (BCC), other type BCC, and squamous cell carcinoma (SCC), respectively. 31 cases were recurrent cancer with various previous treatments. The average distance of maximal microscopic tumor extension peripherally
S49
S50
I. J. Radiation Oncology
● Biology ● Physics
Volume 63, Number 2, Supplement, 2005
beyond a gross lesion was 5.2 mm (range:1–15) for the entire 71 lesions. It was 5.0 mm (range:1–13) for sclerosing BCC, 5.3 mm (range:2–15) for other type BCC, and 5.7 mm (range:2–10) for SCC. The figure shows the probability of clear resection margin vs. the distance beyond clinically delineated gross tumor. In only 62% of cases did 5 mm margin around the clinically delineated tumor border adequately cover the microscopic peripheral tumor extent. A margin of 10 mm was required to provide a 95% chance of obtaining clear resection margins. The microscopic tumor extent was positively correlated with the size of gross lesion (Pearson r ⫽ 0.47, p ⬍ 0.0001), but not with other variables (histology type, location of lesion, and presence/absence of previous treatment history). Conclusions: The peripheral distance of microscopic tumor extension beyond a gross tumor in nonmelanoma skin cancer was variable with a mean of 5.2 mm. The larger the size of a lesion, the greater the extent of microscopic tumor extension. Such information is critical for the proper radiation planning of skin cancer.
82
Sustained Remission Following Radiation Treatment for High-Risk Pigmented Villonodular Synovitis
B. O’Sullivan,1,2 A. Griffin,4 J. Wunder,4,2 P. Marks,7,2 C. Catton,1,2 P. Ferguson,4,2 P. Chung,1,2 R. Kandel,5,2 L. White,6,2 R. Bell3,2 1 Department of Radiation Oncology, Princess Margaret Hospital, Toronto, ON, Canada, 2University of Toronto, Toronto, ON, Canada, 3Department of Surgical Oncology, Princess Margaret Hospital, Toronto, ON, Canada, 4 Division of Orthopaedic Surgery, Mount Sinai Hospital, Toronto, ON, Canada, 5Department of Pathology, Mount Sinai Hospital, Toronto, ON, Canada, 6Department of Medical Imaging, Mount Sinai Hospital, Toronto, ON, Canada, 7 Department of Orthopaedic Surgery, Orthopaedic and Arthritic Institute, Toronto, ON, Canada
Purpose/Objective: Pigmented villonodular synovitis (PVNS) is a rare proliferative process originating from synovial membranes. Usually benign, it may be destructive, resulting in major symptoms and loss of function leading to amputation rarely. There is a paucity of outcome data following radiotherapy in high risk cases. Our purpose was to update a prior experience with extended follow-up and almost three times greater accrual of cases at high risk for recurrence with functional loss including instances where amputation was the sole alternative for symptomatic disease. Materials/Methods: The records of all patients (41 cases) who received radiotherapy for PVNS between 1972 and 2003 were reviewed retrospectively and, since 1986, prospectively. Eligibility included at least one year of follow-up following radiotherapy. Local control was defined as absence of clinical or imaging evidence of disease following treatment in either patients without overt disease at the time of radiotherapy, or in patients with stable disease on serial cross-sectional imaging of gross disease for at least one year following treatment. Results: All cases had pathologic confirmation of diagnosis at our center. 18 had primary and 23 recurrent disease (with a mean of 2 prior surgical procedures). 36 had origin from a joint (most commonly the knee in 37%) and 5 arose in periarticular tendon sheath. All but 1 had both intra- and extraarticular disease and, without exception, the poorer prognosis diffuse subtype of the disease. The majority had one or more additional risk factors including skin, bone, tendon, neurovascular, or muscle group extension and 17 of these lesion exceeded 10 cm in maximum dimension. 21 had gross residual disease at the time of radiotherapy. The mean radiotherapy dose was 38 Gy (range 28 Gy to 50 Gy), the majority receiving 35 Gy in 14 fractions. One patient had the malignant variant of PVNS and is the only patient with clear resection margins consistent with oncologic principles for malignant sarcomas. With a mean follow-up time of 77 months (range 13–337 months), only one patient has shown active disease by the criteria described. Two additional cases (both tendon sheath lesions of the wrist/hand) underwent subsequent biopsies of a palpable asymptomatic stable lesion (⬍1 cm in size). In one this took place 9 years following radiotherapy and he remained without treatment or progression 17 years later; the second had a biopsy 16 years following treatment, had no additional therapy and was well without progression 3 years later. No patient required amputation, and none had evidence of serious radiotherapy complications. Only one patient has developed a second malignancy, specifically a brain tumor but the site of PVNS was the ankle. Conclusions: Moderate dose radiotherapy is a very effective treatment in PVNS and permits local control and avoidance of amputation in very advanced and typically recurrent cases. When treatment is indicated we currently recommend gross total removal of PVNS followed by moderate dose radiotherapy for residual disease where salvage of subsequent recurrence may compromise function. Alternatively control of gross disease can also be expected following radiotherapy.