Prevention of Entero-Atmospheric Fistula: The Initial Closure of the Abdomen.

BACKGROUND AND AIMS: The "Open Abdomen" technique for difficult conditions such as trauma, necrotizing pancreatitis, severe peritonitis, reoperations and transplantations have become a very useful way to save patients. The more severe complication of this method are the enteroatmospheric fistulae with a frequency of 5-75% and a mortality up to 42%. So any effort to prevent these is very essential. The aim of this paper is to present methods of the initial (temporary) closure of the abdomen for the prevention of this catastrophe, when early approximation of the abdominal wall is not feasible. METHODS AND MATERIALS: We present two representative case reports and we describe the use of full thickness or split skin grafts as first step for abdominal closure. RESULTS AND CONCLUSIONS: The outcome of our patients by using tissues for temporary abdominal closure seems to have fewer problems than other methods with synthetic materials. We think that this is a reasonable option for the cases where we cannot achieve approximation of the abdominal wall edges in the early days of an open abdomen.

Evaluation of efficacy and toxicity in two different hypofractionated 3D-conformal external beam radiotherapy schedules in localised muscle invasive bladder cancer.

PURPOSE: To evaluate the efficacy as well as acute and late toxicity of two different accelerated hypofractionated 3D-conformal radiotherapy (Hypo-3DCRT) schedules in patients with bladder cancer. METHODS: Between February 2006 and June 2011, 50 elderly patients with cT1-2N0 bladder carcinoma were treated with Hypo-3DCRT. Mean age was 75 years. All patients were medically inoperable, with poor performance status, who couldn't tolerate either cystectomy or radical external beam irradiation on a daily basis. A dose of 36 Gy in 6 weekly fractions (arm A, N=39) or 39.96 Gy of 3.33 Gy twice daily, once a week, for 6 weeks (arm B, N=11) were prescribed. The primary study endpoints were the evaluation of acute/late gastrointestinal (GI) toxicity according to the EORTC/RTOG scale together with the visual analogue bladder-related pain score (VAS). RESULTS: The GI acute toxicities were: grade 1: arm A 24/39 (61.5%), arm B 9/11 (81.8%); grade 2: arm A 14/39 (35.9%), arm B 1/11 (9.1%); grade 3: arm A 1/39 (9.1%) (x(2), p=0.29). Only grade 1 late GI toxicity was seen and was significantly higher in arm A: arm A 17/39 (43.6%) and arm B 1/11 (9.1%) (x(2), p=0.037). The reduction of VAS score was similar in both arms (p=0.065). The median relapse free survival (RFS) was 15 and 16 months for arm A and B, respectively (log rank, p=0.71). CONCLUSIONS: Beyond the non-randomized design of the trial, the Hypo-3DCRT schedules used appear to be an acceptable alternative to the traditional longer radiotherapy (RT) schedules for elderly patients unfit for daily irradiation.

A weekly hypofractionated radiotherapeutic schedule for bladder carcinoma in elderly patients: local response, acute and late toxicity, dosimetric parameters and pain relief.

PURPOSE: To investigate the early and late toxicity of a hypofractionated radiotherapy (RT) schedule to treat muscle- invasive bladder cancer in relation to radiation parameters according to the organs at risk. METHODS: Forty-three patients with T2-T3 bladder carcinoma were irradiated with a weekly hypofractionated schedule with a total dose of 36 Gy in 6 fractions. Included in this study were elderly patients with poor performance status or unfit for surgery, while they complained of daily pain on urination. Pain evaluation was assessed with the use of the visual analogue scale (VAS) of pain, acute and late toxicities were assessed using the combined RTOG/EORTC criteria by using a dose of 50 Gy (D50), and the relapse free survival (RFS) was estimated from the date of recurrence. RESULTS: No acute side effects were observed in the majority of the patients. Grade I rectal toxicity was registered in 67.4% of the patients, while grade II and III were noted in 30.25% and 2.37percnt; of the patients, respectively. The worst late rectal toxicity was grade I in 30.2% of the patients. The VAS score of pain showed a significant improvement after the hypofractionated schedule. There was a significant correlation between acute and late toxicity on the one hand and the D50 dosimetric parameter on the other. The Kaplan-Meier plot showed a median RFS of 15 months, while age did not have any impact on RFS in patients above or under 75 years of age. CONCLUSION: The performed hypofractionated schedule permitted delivery of an increased radiation dose without increased toxicity, and with a high probability of local control for elderly patients with low survival perspective.

Radiotherapy for Hodgkin's lymphoma: too hard to die?

The treatment of Hodgkin's lymphoma (HL) is associated with significant toxicity. The objective of high quality management is to keep the concept of combined modality, while trying to decrease the radiation dose, to diminish to a great extent the irradiated volume and at the same time to reduce the number of chemotherapy courses, introducing the so-called optimisation. New directives should be followed to obtain more effective treatments of HL. Shorter cycles of chemotherapy and the utilization of modern techniques in radiotherapy (RT) constitute fundamental steps to achieve this objective. Analysis of randomized studies supports the inclusion of reduced-field and dose of RT in the radiotherapeutic treatment options for HL. RT is an integral part of the combined-modality therapy (CMT) of HL.

Gastric cancer and adjuvant chemoradiotherapy: when and where, that's the question.

PURPOSE: Although the incidence of gastric cancer is decreasing, there were still 159,900 new cases and 118,200 deaths in Europe in 2006 representing the 5th highest incidence and 4th highest cause of cancer-related deaths. Postoperative adjuvant chemoradiotherapy has been demonstrated to result in a significant improvement in overall and disease-free survival. We studied the current role of adjuvant chemoradiotherapy in gastric cancer. METHODS: Randomized phase III studies and selected phase II studies for adjuvant chemoradiotherapy in gastric cancer were searched in PUBMED using key words. Also, international treatment guidelines as well as review papers were searched and analysed. RESULTS: Based on the published literature, treatment guidelines and reports from international meetings it is obvious that adjuvant chemoradiotherapy in gastric cancer contributes in improved treatment results. CONCLUSION: Surgical resection remains the cornerstone of curative treatment for gastric cancer. The combination of modern radiotherapy techniques with chemotherapy is feasible, safe and improves overall survival of patients with gastric cancer.

Conventional versus virtual simulation for radiation treatment planning of prostate cancer: final results.

PURPOSE: Radiotherapy is widely used to treat patients with prostate cancer. Using conventional x-ray simulation is often difficult to accurately localize the extent of the tumor, to cover exactly the lymph nodes at risk and shield the organs at risk. We report on the results of a study comparing target localization with conventional and virtual simulation. METHODS: One hundred prostate cancer patients underwent both conventional and virtual simulation. The conventional simulation films were compared with digitally reconstructed radiographs (DDRs) produced from the computed tomography (CT) data. All patients underwent target localization for radical prostate radiotherapy. The treatment fields were initially marked with a conventional portal film on linear accelerator (LINAC), plain x-ray film and available diagnostic imaging. Each patient then had a CT and these simulated treatment fields were reproduced within the virtual simulation planning system. The treatment fields defined by the clinicians using each modality were compared in terms of field area and implications for target coverage. RESULTS: Virtual simulation showed significantly greater clinical tumor volume coverage and less normal tissue volume irradiated compared with conventional simulation (p <0.001). CONCLUSION: CT localization and virtual simulation allow more accurate definition of the clinical target volume. This could enable a reduction in geographical misses, reducing at the same time treatment-related toxicity.

Evaluation of the possible benefits of post-radiotherapy surgery after concomitant chemoradiotherapy with a new radio-sensitizing regimen (irinotecan / CPT-11, interferon A2b and amifostine) for advanced-stage cervical carcinoma. Preliminary results of a pilot phase-II study.

PURPOSE: This phase II pilot study was conducted to evaluate the results of a three-modality approach (which included post-chemoradiotherapy surgery) in advanced-stage cervical carcinomas. PATIENTS AND METHODS: Thirty-six patients underwent either surgery or were put on follow-up after having received radical cervical radiotherapy (RT) combined with radiosensitizing chemoimmunotherapy with irinotecan (CPT-11), interferon (IFN) A2b, and amifostine. The last selection (surgery or follow-up) was based on clinical evaluation (downstaged or not). Feasibility, morbidity, surgical outcome and survival were evaluated. RESULTS: Twenty-six patients had stage IIb and 10 IIIb disease at diagnosis. Sixteen (44%) were clinically downstaged, thus becoming eligible for surgery. Twelve (33%) were operated and the others were put on follow-up. There was no significant increase in treatment-related morbidity of the group of patients receiving three-modality therapy, since only one intraoperative complication had occurred. In 58% of the operated patients, chemoradiotherapy-resistant tumor was found on pathology of the cervical specimens, while 29% of them had lymph nodes infiltrated by the tumor. After a median follow-up of 42.5 months, overall survival (OS) of operated vs. non-operated patients (88 vs. 56%, respectively) show only a trend toward significance (p=0.10). The overall recurrence/metastasis rate was 36.1% and the disease-free survival (DFS) 56% for operated vs. 76% for non-operated patients, respectively (p=0.63). CONCLUSION: These results indicate that post-chemoradiotherapy surgery is justified because of the high rate of residual disease found. Morbidity can be effectively limited with proper patient selection. A considerable survival benefit is expected, although this remains to be confirmed with phase III studies.

European Contegra multicentre study: 7-year results after 165 valved bovine jugular vein graft implantations.

OBJECTIVE: The valved bovine conduit "Contegra" for RVOT reconstruction became available for clinical use within a 100 % source data monitored and echo core lab controlled prospective European Multicentre Study, carried out from 1999 to 2006. We present the results of this study. METHODS: A total of 165 Contegras were implanted in 8 centres. The mean patient age was 3.9 years (2 days - 18 years, median 2.0). Total follow-up was 687 patient years. Diagnoses included: tetralogy of Fallot (64 patients, 39 %), truncus arteriosus (50, 30 %), double outlet right ventricle (16, 10 %), aortic valve disease/Ross procedure (11, 7 %), pulmonary valve atresia (10, 6 %), transposition of the great arteries (10, 6 %), 4 other malformations (2 %). Previous procedures were: 82 patients (50 %) - none; 37 (22 %) - valved conduit implantation; 14 (8 %) aortopulmonary shunt; 6 (4 %) catheter intervention. Follow-up appointments which included standardised echocardiography investigations were scheduled at 1, 3, 6, and 12 months, then annually. We evaluated freedom from death, explantation, intervention, stenosis, insufficiency, and degeneration. Results were stratified by age, diagnosis group and conduit size. RESULTS: The 5-year freedom-from rates were: explantation - 90 % (for patients aged 1 to 10 years) and 68 % (for younger patients); endocarditis - over 92 %; catheter intervention - 74 % (patients with congenital malformations); stenosis - 75 % and more (any group); insufficiency - 50 % (12 and 14 mm diameter conduits); any event - 13 % (patients under 1 year), 58 % (1 to 10 years), 82 % (> 10 years). Trace or mild insufficiency was a frequent, but not progressive finding. Mild calcification was detected in only 8 examinations. CONCLUSIONS: The performance of the Contegra conduit compares well with that of homografts when used to reconstruct paediatric right ventricular outflow tracts.

Surgical treatment of the atrial septal defect in adults: effective reduction in cardiac size and excellent overall clinical outcome.

OBJECTIVE: Atrial septal defect (ASD), one of the commonest congenital heart lesions, is asymptomatic in most cases and therefore remains undiagnosed until adulthood in a significant number of patients. Despite the employment of transcatheter modalities in its treatment, surgery remains a reliable alternative. This study summarizes our experience in surgical correction of ASD in adult patients. METHODS: Over a 9-year period (September 1997-August 2006), 171 patients, 73 males and 98 females, aged 18-72 (median 35) years, underwent surgical repair of ASDs'. Of these, 141 patients (82%) had ASD of the secundum type and 30 (18%) sinus venosus ASD with partial anomalous pulmonary venous connection (PAPVC). Fifteen patients with different principal diagnoses and concomitant ASD's were excluded, as were those with ostium primum ASDs'. Eighty six patients (50%) were asymptomatic and 11 (6.4%) had established arrhythmias. Two patients had recurrent lesions, 5 had a previously failed attempted transcatheter closure of which 3 were admitted as emergencies. All underwent complete surgical repair. RESULTS: Two patients (aged 53 and 69 years) with chronic atrial fibrillation suffered embolic strokes (1.16%), with one of the two subsequently dying from cerebral haemorrhage (0.6%). Other postoperative complications (including atrial arrhythmias) were treated successfully. Median ICU and hospital stay were 1 and 6 days respectively. Significant reduction in heart size was noted postoperatively as defined by the reduction in the cardiothoracic ratio (p=0.003). At mean follow up of 55+/-28 months, there was one late death from heart failure in a patient with advanced preoperative disease. All other patients remain in excellent clinical condition. CONCLUSION: Surgical correction of ASD is associated with low morbidity and mortality. Arrhythmias and their complications could be prevented by early surgical treatment.

Tetralogy of Fallot: influence of right ventricular outflow tract reconstruction on late outcome.

Surgical repair of Tetralogy of Fallot (TOF) is followed by very good early and medium-term results (perioperative mortality < or =5%), but there is increasing awareness of the occurrence of late adverse events: many patients experience progressive right ventricular (RV) dilatation/dysfunction leading to symptomatic right ventricular failure, arrhythmias, need for reoperation(in 5-15% of patients within 5-20 years after initial correction ), and late death. Although some predisposing factors such as complexity of anatomy (borderline pulmonary artery (PA) size, right ventricular outflow tract (RVOT) hypoplasia), age at operation, or prior shunting appear to affect early or late outcome adversely, it is debatable if other factors such as type of repair or use of a transannular patch correlate with poor late outcome or increased reoperation rates. Obviously, if careful study reveals specific modifiable factors predisposing to adverse late events (e.g. component of surgical technique), appropriate modification in surgical management may lead to improved late outcome.

Extracorporeal membrane oxygenation circulatory support after cardiac surgery.

OBJECTIVES: Postcardiotomy acute severe heart failure cannot be managed by medical treatment alone and most often requires some form of mechanical support. In this study we evaluate the efficacy of postoperative extracorporeal membrane oxygenation (ECMO) support following surgery for congenital heart disease (CHD) in infants and children. METHODS: Over a 6-year period from October 1997 to October 2003, 10 patients aged 5 days to 28.5 months (median 3 months) who underwent surgical procedures for CHD received postoperative mechanical support for failing cardiac function despite optimal medical therapy. In 3 patients ECMO was instituted in the operating room (OR) and in 7 patients this was introduced in the intensive care unit (ICU) 2 to 48 (median 20) hours postoperatively. RESULTS: Four patients (40%) were successfully weaned, while support was withdrawn in the remaining 6 due to irreversible vital organ damage. Following successful weaning, one of the survivors died 8 hours later from barotrauma and intrapulmonary hemorrhage, and another died 4 months later from persistent heart failure. The other two patients remain well in NYHA class II. CONCLUSIONS: Despite the adverse effects of ECMO, the methodology provided the necessary support and allowed the failing heart to recover in a number of patients where inotropic support alone proved inadequate.

Phase I study of postoperative radiotherapy with concomitant weekly irinotecan, 5- fluorouracil and folinic acid in locally advanced rectal cancer.

PURPOSE: 5- fluorouracil (5-FU)-based chemotherapy with concomitant pelvic radiotherapy represents the gold standard of the adjuvant treatment of high-risk rectal cancer. This study aimed to determine the maximum tolerated dose (MTD) of weekly irinotecan (CPT-11) when combined with fixed 5FU/FA doses and pelvic irradiation. PATIENTS AND METHODS: Twenty- four patients with stage II or III rectal cancer were accrued. All had undergone curative surgery before entering the study. Standard pelvic radiotherapy was delivered (50.4 Gy, 1.8 Gy/ fraction in 5.5 weeks). The 5-FU/FA doses were 350/250 (mg/m(2)) in the first 6 patients and 250/100 in the remaining patients. Weekly doses of CPT-11 started at 30 mg/m(2) with escalation steps of 10 mg/m(2). CPT-11 was escalated when 3 patients had been monitored for 8 weeks, without a dose limiting toxicity (DLT). RESULTS: Twenty-three out of 24 patients completed the chemoradiation course. Only 1 patient discontinued the treatment due to persistent grade 3 diarrhea. Of the 144 planned weekly chemotherapy cycles, only 7 were omitted as a result of persisting grade 2-3 gastrointestinal toxicity in 3 patients and grade 3 neutropenia in 1 patient. Grade 3 gastrointestinal DLTs were observed at doses at the level of 30/250/100 in 1 patient and 70/250/100 in 2 patients. Late DLTs were severe radiation dermatitis and colitis at 40/ 350/250 (1 patient) and 70/250/100 (2 patients), respectively. With a follow-up of 18 months 20 (83.3%) patients remain disease- free. CONCLUSION: The administration of weekly CPT-11/ 5FU/FA with concomitant pelvic radiotherapy is feasible and effective. This treatment schedule is associated with mild myelosuppression and mild to moderate gastrointestinal toxicity. Caution should be paid on late radiotherapy-induced toxicities. The MTD of weekly CPT-11 is 30 mg/m(2) when combined with 5FU/FA doses (mg/m(2)) of 350sol;250 and reaches 60 mgsol;m(2) with lower doses of 5FU/FA (250/100).

The RACOX phase I study: radiation (RA), capecitabine (C) and oxaliplatin (OX) as adjuvant treatment of stage II and III rectal cancer.

PURPOSE: The aim of this phase I trial was to deter- mine the maximum tolerated dose (MTD) of adjuvant che- motherapy (CT) with oxaliplatin in combination with capecitabine during concomitant pelvic radiotherapy (RT) in patients with rectal cancer. PATIENTS AND METHODS: Eligible patients had pathological stage II (T3-4N0M0) or III (any T N1-2M0) rectal adenocarcinoma, and no prior treatment other than curative resection. Fixed capecitabine dose (825 mg/m(2) bid on days 1-14 and 22-35) was given and external beam RT was delivered to the pelvis (50.4 Gy in 27 fractions in 5.5 weeks, with field reduction after 45 Gy in linear accelerator, 18Mev). Oxaliplatin was tested at 4 dose levels: 100, 110, 120 and 130 mg/m(2). The dose of oxaliplatin was escalated when all 3 entered patients at each level had been monitored for at least 8 weeks after the CT/RT course without dose limiting toxicities (DLTs). In the presence of a DLT at any dose level, a further 3 patients were enrolled. If only 1 of the 6 patients experienced a DLT, escalation could proceed. The MTD was defined as the level at which >/= 2 of 3 to 6 patients experienced DLTs. Fifteen patients (10 males and 5 females, median age 62 years) were enrolled at oxaliplatin dose levels of 100 (n=3), 110 (n=3), 120 (n=3) and 130 mg/m(2) (n=6). RESULTS: All patients completed the planned CT/RT course. Dose reduction or delay of the 2nd CT cycle was not required. No DLTs were observed at all dose levels. Overall, gastrointestinal and neurological toxicities were mild and transient. Toxicities included non-dose-limiting nausea / vomiting, diarrhea, dysesthesias in 2 level III and in 1 level IV patients. Grade II myelotoxicity, mainly neutropenia, was seen in 6 patients. With a median follow-up of 4 months (range 2-12) after the completion of CT/RT, late toxicities were restricted to grade II radiation colitis and dermatitis in 2 and 2 patients, respectively. CONCLUSION: The combination of pelvic RT, capecitabine and 3-weekly oxaliplatin is feasible and well tolerated. The MTD was not reached up to the dose of 130 mg/m(2) of oxaliplatin, which is the recommended dose.

Early results after transatrial/transpulmonary repair of tetralogy of Fallot.

OBJECTIVES: Right ventricular (RV) dysfunction is a significant cause of morbidity and mortality after surgical correction of tetralogy of Fallot (TOF). Transatrial/transpulmonary repair avoids a ventriculotomy (in contrast to the transventricular approach) emphasizing maximal preservation of RV structure and function. We have adopted this technique as less traumatic for the right ventricle. This study evaluates the early surgical results of our approach. METHODS: Between September 1997 and July 2001, 110 consecutive patients with TOF were referred to our unit for surgical therapy. Of these, 14 were unsuitable for repair and underwent aortopulmonary shunting+/-pulmonary artery patching. In the remaining 96 patients (median age 1.4 years), complete transatrial/transpulmonary repair was performed. Previously placed shunts (ten patients) were taken down and any secondary stenoses or branch pulmonary artery distortion repaired. In all cases, subpulmonary resection and ventricular septal defect (VSD) closure were accomplished transatrially. Whenever pulmonary valvotomy and valve ring widening were necessary, it was achieved through a pulmonary arteriotomy. In 84 patients the main pulmonary artery was augmented with an autologous pericardial patch, and in 23 the patch was extended to pulmonary artery branch(es). A limited (<1cm ) or extended (>1cm, but

Phase II randomized trial of temozolomide and concurrent radiotherapy in patients with brain metastases.

PURPOSE: To determine the efficacy, tolerability, and safety of concurrent temozolomide and radiotherapy in patients with previously untreated brain metastases. PATIENTS AND METHODS: Fifty-two patients with brain metastases from solid tumors were randomized to oral temozolomide (75 mg/m(2)/d) concurrent with 40-Gy fractionated conventional external-beam radiotherapy (2 Gy, 5 d/wk) for 4 weeks versus 40-Gy radiotherapy alone. The group receiving temozolomide and radiotherapy continued temozolomide therapy (200 mg/m(2)/d) for 5 days every 28 days for an additional six cycles. The primary end points were radiologic response and neurologic symptom evaluation. RESULTS: The objective response rate was significantly (P =.017) improved in patients receiving temozolomide and radiotherapy versus radiotherapy alone. Among 24 patients assessable for response in the temozolomide group, 23 (96%) of 24 responded, including nine (38%) patients with a complete response and 14 (58%) patients with a partial response. With radiotherapy alone, 14 (67%) of 21 assessable patients responded, including seven (33%) complete responses and seven (33%) partial responses. There was marked neurologic improvement in the group receiving temozolomide, and the proportion of patients requiring corticosteroids 2 months after treatment was lower in the temozolomide group compared with radiotherapy alone (67% v 91%, respectively). Daily temozolomide concurrent with radiotherapy was generally well tolerated; however, grade >or= 2 nausea (48% v 13%, P =.13) and vomiting (32% v 0%, P =.004) were significantly increased in the temozolomide group. Hematologic toxicity was predictable and reversible. CONCLUSION: Temozolomide is safe, and a significant improvement in response rate was observed when administered in combination with radiotherapy in patients with previously untreated brain metastases. A larger randomized trial is warranted to verify these results.

Identification and catheter ablation of extracardiac and intracardiac components of ligament of Marshall tissue for treatment of paroxysmal atrial fibrillation.

INTRODUCTION: The ligament of Marshall is a left atrial neuromuscular bundle with sympathetic innervation that may be a source of atrial fibrillation (AF)-inducing automatic activity. METHODS AND RESULTS: Twenty-four patients with paroxysmal AF (including 18 with adrenergic AF) and 25 with other arrhythmias underwent catheter mapping. In cases of adrenergic AF, radiofrequency ablation was attempted when Marshall potentials were recorded. Patients were followed for 2 months before and 11.2 +/- 4.2 months after the procedure. Catheterization of the distal superoposterior coronary sinus was feasible in 14 patients with AF (10 with adrenergic AF) and 12 patients without AF. A discrete Marshall potential was recorded in 12 patients with AF versus 3 patients without AF (P = 0.004). In 10 patients with adrenergic AF, this potential followed the atrial electrogram during sinus rhythm by 26 +/- 5 msec on left atrial recordings and 24 +/- 4 msec on coronary sinus recordings, and preceded it during atrial ectopy by 29 +/- 5 msec and 26 +/- 5 msec, respectively. It was abolished by epicardial (n = 1), endocardial (n = 4), or combined epicardial and endocardial ablation (n = 5). Seven patients with ablation showed significant reductions in adrenergic AF, whereas no significant change was seen in 8 adrenergic AF patients not undergoing ablation (P = 0.004). No improvement was seen in 3 of 4 patients with only endocardial ablation, whereas all 6 patients with epicardial ablation improved (P = 0.033). CONCLUSION: Recording of Marshall potential is feasible in patients with paroxysmal AF. Combined epicardial and endocardial catheter ablation of ligament of Marshall tissue may reduce the paroxysms of adrenergic AF.

Immediate post-operative balloon dilatation of neonatal long segment stenosis of the descending thoracic aorta.

During surgical repair of a neonatal coarctation it was recognized that this was a rare, previously undescribed form of stenosis of the entire descending thoracic aorta. A few hours after the end-to-end surgical repair, the child underwent successful balloon angioplasty, involving the entire descending thoracic aorta, and in which we intentionally avoided the surgical site.

Decorin binds near the C terminus of type I collagen.

Decorin belongs to a family of small leucine-rich proteoglycans that are directly involved in the control of matrix organization and cell growth. Genetic evidence indicates that decorin is required for the proper assembly of collagenous matrices. Here, we sought to establish the precise binding site of decorin on type I collagen. Using rotary shadowing electron microscopy and photoaffinity labeling, we mapped the binding site of decorin protein core to a narrow region near the C terminus of type I collagen. This region is located within the cyanogen bromide peptide fragment alpha1(I) CB6 and is approximately 25 nm from the C terminus, in a zone that coincides with the c(1) band of the collagen fibril d-period. This location is very close to one of the major intermolecular cross-linking sites of collagen heterotrimers. Thus, decorin protein core possesses a unique binding specificity that could potentially regulate collagen fibril stability.