Radiation oncology investigations最新文献

A five-field conformal technique with three-dimensional radiation therapy treatment planning (3-DRTP) has been shown to permit better definition of the target volume for lung cancer, while minimizing the normal tissue volume receiving greater than 50% of the target dose. In an initial study to confirm the safety of conventional doses, we used the five-field conformal 3-DRTP technique. We then used the technique in a second study, enhancing the therapeutic index in a series of 42 patients, as well as to evaluate feasibility, survival outcome, and treatment toxicity. Forty-two consecutive patients with nonsmall-cell lung carcinoma (NSCLC) were evaluated during the years 1993-1997. The median age was 60 years (range 34-80). The median radiation therapy (RT) dose to the gross tumor volume was 6,300 cGy (range 5,000-6,840 cGy) delivered over 6 to 6.5 weeks in 180-275 cGy daily fractions, 5 days per week. There were three patients who received a split course treatment of 5,500 cGy in 20 fractions, delivering 275 cGy daily with a 2-week break built into the treatment course after 10 fractions. The stages of disease were II in 2%, IIIA in 40%, IIIB in 42.9%, and recurrent disease in 14.3% of the patients. The mean tumor volume was 324.14 cc (range 88.3-773.7 cc); 57.1% of the patients received combined chemoradiotherapy, while the others were treated with radiation therapy alone. Of the 42 patients, 7 were excluded from the final analysis because of diagnosis of distant metastasis during treatment. Two of the patients had their histology reinterpreted as being other than NSCLC, 2 patients did not complete RT at the time of analysis, and 1 patient voluntarily discontinued treatment because of progressive deterioration. Median follow-up was 11.2 months (range 3-32.5 months). Survival for patients with Stage III disease was 70.2% at 1 year and 51.5% at 2 years, with median survival not yet reached. Local control for the entire series was 23.3+/-11.4% at 2 years. However, for Stage III patients, local control was 50% at 1 year and 30% at 2 years. Patients who received concurrent chemotherapy had significantly improved survival (P = 0.002) and local control (P = 0.004), compared with RT alone. Late esophageal toxicity of > or =Grade 3 occurred in 14.1+/-9.3% of patients (3 of 20) receiving combined chemoradiotherapy, but in none of the 15 patients treated with RT alone. Pulmonary toxicity limited to Grades 1-2 occurred in 6.8% of the patients, and none developed > or =Grade 3 pulmonary toxicity. Patients with locally advanced NSCLC, who commonly have tumor volumes in excess of 200 cc, presenta challenge for adequate dose delivery without significant toxicity. Our five-field conformal 3-DRTP technique, which incorporates treatment planning by dose/volume histogram (DVH) was associated with minimal toxicity and may facilitate dose escalation to the gross tumor.

Sarcoidosis is a chronic, multisystemic disorder of unknown etiology. The incidence of central nervous system involvement is as high as 5%. Although steroids have been the cardinal treatment for sarcoidosis, many patients become symptomatically unresponsive to them. Other patients may suffer from glucose intolerance, cataracts, and obesity, which are adverse effects of high-dose steroids. Various reports in the literature suggest that some chemotherapeutic agents and/or radiation may be useful in these situations. We present three patients with neurosarcoidosis who were treated with radiation at a single institution. We also review previous reports on radiation-treated neurosarcoid patients. While the results vary, some patients clearly derive symptomatic benefits from low-dose radiation. Since the side effects of low-dose cranial irradiation are minimal, it may be prudent to use radiation therapy for patients who are refractory to steroids or who suffer adversely from high-dose steroids.

Telomeres play an important role in maintaining chromosomal stability and are often shortened in transformed cells. p53 is the most commonly mutated gene in cancers and its status is thought to reflect the level of genomic stability. We measured telomeric length by Southern blot analysis in cells from cancer-prone syndromes and in selected cancer cells with altered p53 status. Mean telomeric lengths in the cancer-prone syndromes Li-Fraumeni syndrome, Fanconi's anemia, and ataxia telangiectasia, were shorter in the affected individuals than in their unaffected parents. We also found that altered p53 expression in selected cancer cell model systems may be associated with shortened telomeric length, but did not appear to be associated with significant alterations in telomerase activity.

Advanced squamous cell carcinomas of the head and neck are difficult to control despite optimal surgery, radiotherapy and/or chemotherapy, and the tumors are usually not immunogenic. Because of the anatomic accessibility of the tumors, local adoptive immunotherapy of these tumors is feasible and may interact with radiotherapy to retard tumor growth. It is hypothesized that antigens released from tumor cells injured by radiation may stimulate, in the presence of interleukin-2, an enhanced immunocytodestruction of live tumor cells by adoptively transferred lymphokine activated killer cells and recruited tumor cytotoxic cells. DBA/2 mice were injected subcutaneously with 5 x 10(5) syngeneic squamous cell carcinoma cells in the thigh and the resulting tumors were treated for two weeks with daily peritumoral injections of interleukin-2 (1,000 International Units) or saline, four radiation treatments of 625 cGy each, and four peritumoral injections of 10(7) lymphokine activated killer cells. The results suggested that radiotherapy combined with peritumoral injection of lymphokine activated killer cells and interleukin-2 resulted in a significant reduction (P < 0.01) of tumor size whereas radiation alone, at the same dose, failed to produce a significant effect. Such results may have direct clinical application in enhancing the response of tumors to radiotherapy and in reducing the incidence of tumor recurrence.

To determine the effect of time between prostate brachytherapy and evaluation CT scan on calculated target coverage. CT scans from 11 consecutive, unselected patients with stage T1 or T2 prostatic carcinoma who had transperineal I-125 implants at MSKCC in 1996 were analyzed for target coverage at 0, 2, and 6 months after implantation. The outer margins of the prostate were outlined on each CT section by a single investigator. In each CT plane, the prescription isodose (150 Gy) was overlaid on the target contour from the postimplant CT to calculate the integral Dose-Volume Histogram. The postimplant target volume on the day of the implant ranged from 93% to 160% of the preimplant volume (average: 117%). In all patients, the target size returned to the preimplant size or smaller within 2 months of the procedure and was relatively stable between 2 to 6 months. Immediately following the implant, an average of 84% of the target (range: 73-98%) was covered by the 150 Gy isodose line. Consistent with changes in the target volume over time, the target coverage increased from an average of 84% to 90% between 0 to 2 months and did not change substantially between 2 and 6 months. There was minimal source loss from the target area after the implant. It was concluded that temporary, postimplant swelling will increase the target volume, making target coverage inferior to what would be calculated if a dosimetry scan was taken sometime later, after the acute swelling has subsided. Until the clinical significance of the effect of postimplant volume changes is better defined, we are continuing to obtain evaluation scans on the day of the implant.

Mastectomy will continue to play a substantial role in the treatment of breast cancer, because many women either are not candidates for or do not desire to have breast conservation. Many patients treated with mastectomy will desire reconstruction, and many of these will be advised to receive adjuvant radiotherapy, which has been shown to increase overall survival in certain high risk patients. There continues to be considerable controversy regarding the compatibility of radiation therapy and breast reconstruction due to increased complications and decreased cosmetic outcome. These can be minimized by careful modern surgical and radiation techniques, and in most cases the result is acceptable, including for reconstructions with prosthetic implants as well as autogenous myocutaneous flaps.

The purpose of this work was to investigate how a recently developed MRI-based post-implant dosimetric analysis technique for ultrasound guided transperineal interstitial permanent prostate brachytherapy (TIPPB) compared with the currently accepted CT-based technique. The study was based upon 3-mm MRI and CT scans of 15 patients who had received either 125I or 103Pd implantation. All images were acquired on post-operative day 1 and within 1 hr of each other. Prostate volumes were determined by the same physician. Sources were digitized and calculations performed using an in-house treatment planning system with a nearest neighbor seed sorting routine and AAPM TG43 formalism. Prostate volume, geometric source distribution spread (rcom), dose volume histogram (DVH), and tumor control probability (TCP) calculations were performed from both image sets. Differences in source localization were evaluated by comparing source spread and prescription isodose volumes. Differences in dosimetric analysis were evaluated through prostate-specific DVH and TCP comparisons. Prostate volume as determined from MRI was larger than that of CT by an average of +9.1% (R = 0.70). Calculated rcom was smaller by an average of -0.9 mm (R = 0.81). Isodose volumes at 80, 90, 100, and 150% of the prescription dose differed by an average of +2.5, +2.9, -2.9, and +4.8%, respectively (R = 0.97, 0.98, 0.98, and 0.91). Percentage volume of the prostate encompassed by 80, 100, and 150% of the prescription dose differed by an average of -0.9, -0.9, and -0.1%, respectively (R = 0.34, 0.35, and 0.35). TCP differed by an average of -0.8% (R = 0.37). The results of this study further support our initial findings that MRI may be used to reliably localize the implanted sources for TIPPB. This study also demonstrated that MRI-based post-implant dosimetric analysis is possible. However, it is evident that differences in prostate localization from MRI to CT can result in significantly different assessments of prostate volume coverage. There is clearly a need to further quantify the differences between these two imaging modalities in this application and address whether greater accuracy in describing the dose-volume relationship based on improvements in visualization of the prostate gland from MRI will translate into improved correlation with treatment outcome.

The purpose of this work is to compare bladder and rectal dose rates in brachytherapy for carcinoma of the cervix using two different dosimetry systems: traditional orthogonal radiograph-based dosimetry vs. computed axial tomography tandem and ovoids (CATTO) dosimetry. Twenty-two patients with carcinoma of the uterine cervix received the brachytherapy component of their radiotherapy with a computed-tomography compatible Fletcher-Suit-Delclos device. A total of 27 implants were performed. The average maximum bladder dose (Bmax) for the implants was 85.8 cGy/hr using the CATTO system as compared to 42.6 cGy/hr using traditional dosimetry, (P < 0.005). The average maximum rectal dose (R.) using the CATTO system was 59.2 cGy/hr as compared with 46.3 cGy/hr using the traditional system (P < 0.05). The traditional methods for choosing points to determine bladder and rectal dose rates underestimated the true Bmax in all cases and the R. in most. Based on the complication rates published in the literature, it is likely that the maximum tolerance dose of both the rectum and bladder, but especially the bladder, is higher than previously thought.

Merkel cell carcinoma is a rare, aggressive neuroendocrine tumor of the skin with a predisposition for local regional and distant spread. Radiotherapy after wide local excision has improved local control, but distant spread continues to be a significant problem. This is an update of our experience in the treatment of Merkel cell carcinoma at the University of Florida. Of 24 patients who were treated for Merkel cell carcinoma between 1984 and 1996, 18 patients were treated at the time of the initial diagnosis, and six were treated after local-regional recurrence. Of the 18 previously untreated patients, 13 had primary sites in the head and neck region, and five had primary sites elsewhere. Minimum follow-up was 1 year; no patient was lost to follow-up. The 5-year absolute survival, cause-specific survival, and local-regional control rates for the entire group were 27%, 31%, and 78%, respectively. Patients who were treated with radiotherapy at the time of initial presentation had 5-year absolute survival, cause-specific survival, and local-regional control rates of 38%, 44%, and 73%, respectively. Most deaths were due to distant metastasis. Site of the primary tumor (head and neck versus other) was not associated with any difference in the outcome. Of six patients who were treated at the time of local-regional recurrence, five developed distant metastasis at 3-19 months (median 8 months) from the time of treatment. One patient was alive and without evidence of disease 13 months after treatment. All patients who were treated at the time of local-regional recurrence had local-regional control after radiotherapy at 3-30 months (median 8 months). Wide local excision and radiotherapy is effective local-regional treatment for Merkel cell carcinoma of the skin, but distant metastasis remains a significant problem in this disease. The role and effectiveness of chemotherapy as part of the initial treatment remains to be defined.