Bleomycin-induced increase of collagen turnover in IMR-90 fibroblasts: an in vitro model of connective tissue restructuring during lung fibrosis.

Late-log-phase IMR-90 human fetal lung fibroblasts were incubated with bleomycin sulfate for 48 hr. The culture medium was removed and replaced with serum-free medium and [5-3H]proline. The cells were then incubated for increasing time intervals. The cells and culture medium were collected, and radioactive proline incorporated into collagen and noncollagen protein was determined. Intracellular collagen synthesis was selectively increased. Furthermore, polysomes isolated from bleomycin-treated cells synthesized significantly more collagen in the wheat germ lysate than did control polysomes. Prolyl hydroxylase activity was also increased significantly in the bleomycin-treated cells. Free and peptide-bound radioactive hydroxyproline in the cells and medium was greatly increased in bleomycin-treated cells, which indicates increased collagen degradation. The results demonstrate that, although collagen synthesis in lung fibroblasts is increased by bleomycin, the newly synthesized collagen is rapidly degraded in both the cell layer and the medium. This increased collagen degradation may be responsible for the remodeling which takes place during lung fibrosis.

Optimal radiotherapy for prostate cancer: predictions for conventional external beam, IMRT, and brachytherapy from radiobiologic models.

PURPOSE: To determine, on the basis of radiobiological models, optimal modalities of radiotherapy for localized prostate cancer, and to provide a rational basis for therapeutic decisions. METHODS AND MATERIALS: An algorithm based on extensions to the linear-quadratic (LQ) cell survival model is constructed for fractionated and protracted irradiation. These radiobiological models include prostate tumor cell line-derived LQ parameters, clonogen repopulation, repair of sublethal damage, hypoxia, and radioisotope decay. In addition, dose inhomogeneities for both IMRT and brachytherapy (125I and 103Pd) from patient-derived Dose Volume Histograms (DVH), as well as dose escalation, are incorporated. Three risk groups are defined in terms of sets of biologic parameters tailored to correspond to clinical risk groups as follows: Favorable-iPSA <10 and bGS < or =6 and stage T2; Intermediate-one parameter increased; and Unfavorable-two or more parameters increased. Tumor control probabilities (TCP) are predicted for conventional external beam radiotherapy (EBRT, including 3D-CRT), intensity modulated radiotherapy (IMRT), and permanent brachytherapy. RESULTS: Brachytherapy is less susceptible to variations in alpha/beta than EBRT and more susceptible to variations in clonogen potential doubling time (Tp). Our models predict TCP consistent with the bNED results from recent dose escalation trials and long-term outcomes from brachytherapy. TCP from IMRT are systematically superior to those from conventional fractionated RT, and suggests its possible use in dose escalation without additional dose to surrounding normal tissues. For potentially rapidly dividing tumors (Tp < 30 days) 103Pd yields superior cell kill compared with 125I, but for very slowly proliferating tumors the converse is suggested. Brachytherapy predicts equivalent or superior TCP to dose escalated EBRT. For unfavorable risk tumors, combined 45 Gy EBRT+brachytherapy boost predicts superior TCP than with either modality alone. CONCLUSIONS: The radiobiological models presented suggest a rational basis for choosing among several radiotherapeutic modalities based on biologic risk factors. In addition, they suggest that IMRT may potentially be superior to 3D-CRT in allowing dose escalation without increased morbidity, and that brachytherapy, as monotherapy or as boost, may achieve superior tumor control compared with dose escalation 3D-CRT. The latter conclusion is supported by clinical data.

Clinically evident fat necrosis in women treated with high-dose-rate brachytherapy alone for early-stage breast cancer.

PURPOSE: To investigate the incidence of and variables associated with clinically evident fat necrosis in women treated on a protocol of high-dose-rate (HDR) brachytherapy alone without external-beam whole-breast irradiation for early-stage breast carcinoma. METHODS AND MATERIALS: From 6/1997 until 8/1999, 30 women diagnosed with Stage I or II breast carcinoma underwent surgical excision and postoperative irradiation via HDR brachytherapy implant as part of a multi-institutional clinical Phase I/II protocol. Patients eligible included those with T1, T2, N0, N1 (< or = 3 nodes positive), M0 tumors of nonlobular histology with negative surgical margins, no extracapsular lymph-node extension, and a negative postexcision mammogram. Brachytherapy catheters were placed at the initial excision, re-excision, or at the time of axillary sampling. Direct visualization, surgical clips, ultrasound, or CT scans assisted in delineating the target volume defined as the excision cavity plus 2-cm margin. High activity (192)Ir (3-10 Ci) was used to deliver 340 cGy per fraction, 2 fractions per day, for 5 consecutive days to a total dose of 34 Gy to the target volume. Source position and dwell times were calculated using standard volume optimization techniques. Dosimetric analyses were performed with three-dimensional postimplant dose and volume reconstructions. The median follow-up of all patients was 24 months (range, 12-36 months). RESULTS: Eight patients (crude incidence of 27%) developed clinically evident fat necrosis postimplant in the treated breast. Fat necrosis was determined by clinical presentation including pain and swelling in the treated volume, computed tomography, and/or biopsy. All symptomatic patients (7 of 8 cases) were successfully treated with 3 to 12 months of conservative management. Continuous variables that were found to be associated significantly with fat necrosis included the number of source dwell positions (p = 0.04), and the volume of tissue which received fractional doses of 340 cGy, 510 cGy, and 680 cGy (p = 0.03, p = 0.01, and p = 0.01, respectively). Other continuous variables including patient age, total excised tissue volume, tumor size, number of catheters, number of days the catheters were in place, planar separation, dose homogeneity index (DHI), and uniformity index (UI) were not significant. Discrete variables including the presence/absence of DCIS, sentinel versus full axillary nodal assessment, receptor status, presence/absence of diabetes, and the use of chemotherapy or hormone therapy were not found to have a significant association with the risk of fat necrosis. CONCLUSIONS: In this study of HDR brachytherapy of the breast tumor excision cavity plus margin, treatment was planned and delivered in accordance with the dosimetric parameters of the protocol resulting in a high degree of target volume dose homogeneity. Nonetheless, at a median follow-up of 24 months, a high rate of clinically definable fat necrosis occurred. The overall implant volume as reflected in the number of source dwell positions and the volume of breast tissue receiving fractional doses of 340, 510, and 680 cGy were significantly associated with fat necrosis. Future dosimetric optimization algorithms for HDR breast brachytherapy will need to include these factors to minimize the risk of fat necrosis.

Three-dimensional conformal radiotherapy for early stage prostatic cancer: techniques, outcomes, and possible pitfalls.

Advances in radiation therapy have led to the development of multiple methods to deliver radiotherapy accurately to a defined three-dimensional target. This technology is most appropriate in the management of early stage prostatic cancer. Precise delivery of radiotherapy can control prostate cancer while minimizing normal tissue (e.g., bladder and rectum) complications.

Variation of corticosteroid-induced inhibition of collagen synthesis at equivalent anti-inflammatory doses.

At equivalent anti-inflammatory doses of corticosteroids, granuloma growth is not linearly related to the inhibition of granuloma collagen synthesis. However, the inhibition of granuloma collagen synthesis is linearly related to the inhibition of skin collagen synthesis. Therefore the decrease of collagen synthesis by corticosteroids is not related to anti-inflammatory activity but is related to the specific corticosteroid used.

Collagen lysyl oxidase activity in the lung increases during bleomycin-induced lung fibrosis.

Intratracheal administration of bleomycin caused pulmonary fibrosis in rats. Bleomycin sulfate (640 micro grams/165 g b.wt. in 0.5 ml of sterile saline) was instilled Intratracheally into male Fisher 344 rats (169 +/- 5 g), whereas control animals received 0.5 ml of sterile saline by the same route. One, 3, 7, 14, 28 and 322 days after instillation, the animals were killed, the lungs were homogenized in 6 M urea, 0.01 M NaCl, 0.001 M potassium phosphate (pH 8.3) and the homogenates were subjected to ultracentrifugation. The 106,000 x g supernate was assayed for lysyl oxidase activity. Total lung hydroxyproline and desmosine content was determined at each time point. Lysyl oxidase specific activity in the lung was elevated significantly 3 days after bleomycin treatment, peaked 14 days after bleomycin treatment at 230% above the control value and was returned toward normal 28 days after treatment. The increase of lysyl oxidase activity preceded the maximal increase of total lung hydroxyproline and desmosine which occurred 28 days after bleomycin instillation.

Dexamethasone decreases the amounts of type I procollagen mRNAs in vivo and in fibroblast cell cultures.

Dexamethasone treatment of neonatal chicks resulted in a time- and dose-dependent selective decrease of skin collagen synthesis. Total RNA of chick skin was isolated and hybridized to the cloned cDNAs pCg54 for pro-alpha 1 (I) mRNA and pCg45 for pro-alpha 2(I) mRNA. RNA isolated from the total skin of chicks receiving various doses of dexamethasone had dose-related decreases of pro-alpha 1 (I) and pro-alpha 2(I) mRNAs. The decrease of type I procollagen mRNAs for various doses of dexamethasone were similar to the decreases observed for collagen synthesis in vivo. Dexamethasone treatment of chick skin and chick lung fibroblasts resulted in a selective decrease of procollagen synthesis. A dose-related decrease of procollagen synthesis was observed with chick skin fibroblasts. Dexamethasone-treated chick skin and chick lung fibroblasts had decreased levels of pro-alpha 1 (I) and pro-alpha 2(I) mRNAs as determined by solid support hybridization with pCg54 and pCg45. The dexamethasone-mediated decreases of type I procollagen mRNAs in skin fibroblasts and lung fibroblasts were similar to the decreases observed in procollagen synthesis.

High dose radiation therapy and chemotherapy as induction treatment for stage III nonsmall cell lung carcinoma.

BACKGROUND: The current study was conducted to review the authors' experience in treating consecutive patients with American Joint Committee on Cancer (1997 revision) Stage III nonsmall cell lung carcinoma with aggressive preoperative chemoradiation followed by surgical resection. METHODS: The records of all patients who received preoperative chemoradiation were evaluated. Patients received 2 cycles of concurrent cisplatin and etoposide with 5940 centigrays of radiation therapy. They then were reevaluated to determine whether they were surgical candidates. If so, resection of the primary tumor with mediastinal lymph node dissection was performed 4-6 weeks after the completion of preoperative treatment. After adequate healing, an additional four cycles of cisplatin/etoposide or carboplatin/paclitaxel was given. RESULTS: Forty-two patients received preoperative chemoradiation, 33 of whom underwent surgical resection (79%), including 9 patients who underwent pneumonectomies. Complete pathologic responses were observed in 27% of these patients. Postoperative complications were noted in 21% of the patients and included persistent air leak, supraventricular arrhythmia, and empyema. There were no reported treatment-related deaths. The median follow-up was 26 months. The overall 5-year survival rate for all patients was 36.5% and was 45. 3% for patients who underwent resection. A trend toward increased 5-year survival was observed in patients who had a complete pathologic response (57.1%). Univariate analysis revealed the N stage classification to be significant for predicting a complete response. Patterns of failure revealed the brain to be the most common site of first recurrence (50%) and the only site of recurrence in 36% of patients. There was only one case of local failure. CONCLUSIONS: Preoperative chemoradiation using high radiation doses is feasible with acceptable toxicity. The results of the current study suggest an increased complete pathologic response rate and increased overall survival rate compared with reports in the published literature.