Biomedical subjects

Tony Woo

Publications and source records attributed to Tony Woo.

6 recordsLinked to original sources

PubMed2005

What is the microscopic tumor extent beyond clinically delineated gross tumor boundary in nonmelanoma skin cancers?

PURPOSE: To quantify the microscopic tumor extension beyond clinically delineated gross tumor boundary in nonmelanoma skin cancers. METHODS AND MATERIALS: A prospective, single arm, study. Preoperatively, a radiation oncologist outlined the boundary of a gross lesion, and drew 5-mm incremental marks in four 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 presurgical 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. The distance of microscopic tumor extension beyond a gross lesion varied from 1 mm to 15 mm, with a mean of 5.2 mm. 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, but not with other variables. CONCLUSIONS: The distance of microscopic tumor extension beyond a gross nonmelanoma skin cancer was variable, with a mean of 5.2 mm. Such information is critical for the proper radiation planning of skin cancer therapy.

Adult↗

PubMed2005

Effect of androgen suppression on hemoglobin in prostate cancer patients undergoing salvage radiotherapy plus 2-year buserelin acetate for rising PSA after surgery.

PURPOSE: To examine the effect of 2-year androgen suppression (AS) on the pattern and extent of hemoglobin (Hb) change. METHODS AND MATERIALS: The basis of this report was a Phase II study evaluating a combined treatment of salvage radiotherapy plus 2-year AS for a rising prostate-specific antigen level after surgery. Patients had laboratory tests performed, including Hb and serum testosterone, and answered a quality-of-life questionnaire (European Organization for Research and Treatment of Cancer Quality-of-life Questionnaire 30 item) at regular intervals during the AS and post-AS period. The pattern and extent of the change in Hb was analyzed in relation to the testosterone level. The clinical significance of the Hb change was evaluated with a correlation analysis between Hb and the three specific domains of the questionnaire (Global Health Status, Physical Functioning, and Fatigue). RESULTS: Of a total of 74 accrued patients, 69 were identified as eligible for this report. The median patient age was 70 years. The median follow-up was 38.6 months. The mean Hb was 150.7 g/L at baseline and declined with radiotherapy by 5.9 g/L. The maximal Hb drop during AS was 16.0 g/L (p <0.0001), occurring at 16 months after the initiation of AS. Hb recovery in the post-AS period was slow. The decline and recovery of the mean Hb and hematocrit followed that of testosterone. The three quality-of-life domains did not show any significant correlation with the change in Hb. CONCLUSION: Two-year AS resulted in a statistically significant drop in the mean Hb, but had no clinically apparent adverse effect. The pattern of Hb change was similar to that of testosterone change.

Aged↗

PubMed2005

Long-term outcome of postorchiectomy surveillance for Stage I testicular seminoma.

PURPOSE: To examine the long-term outcome and patterns of relapse in clinical Stage I testicular seminoma managed with surveillance alone after radical inguinal orchiectomy. METHODS AND MATERIALS: This was a prospective, single-arm study. Patients with Stage I testicular seminoma were treated with surveillance alone in accordance with regular, predefined, schedules and investigations. RESULTS: The study accrued a total of 88 patients between 1985 and 1996. The median age at diagnosis was 34 years. The median tumor size was 3.5 cm. The median follow-up as of June 2003 was 12.1 years. Only 3 patients were lost to follow-up. Of the 88 patients, 71 remained free of relapse and 17 did not. The actuarial relapse-free rate was 83%, 80%, and 80% at 5, 10, and 15 years, respectively. Most relapses (15 of 17) were below the diaphragm. Of the 17 patients with relapse, 14 were treated with radiotherapy and 3 with combination chemotherapy. Only 1 had a second relapse and was further salvaged by chemotherapy. All 17 relapsed patients remained free of recurrence after salvage treatment. None died of seminoma. The statistically significant predictive factor for relapse on the Cox proportional hazards model was the presence of rete testis invasion (hazard ratio 3.5, p = 0.03). CONCLUSION: Surveillance with the reservation of radiotherapy or chemotherapy for salvage of relapse is a safe alternative to upfront postoperative adjuvant therapy for Stage I testicular seminoma.

Adult↗

PubMed2005

Inverse vs. forward breast IMRT planning.

Breast intensity-modulated radiation therapy (IMRT) improves dose distribution homogeneity within the whole breast. Previous publications report the use of inverse or forward dose optimization algorithms. Because the inverse technique is not widely available in commercial treatment planning systems, it is important to compare the 2 algorithms. The goal of this work is to compare them on a prospective cohort of 30 patients. Dose distributions were evaluated on differential dose-volume histograms using the volumes receiving more than 105% (V(105)) and 110% (V(110)) of the prescribed dose, and on the maximum dose (D(max)) or hot spot and the sagittal dose gradient (SDG) being the gradient between the dose on inframammary crease and the dose prescribed. The data were analyzed using Wilcoxon signed rank test. The inverse planning significantly improves the V(105) (mean value 9.7% vs. 14.5%, p=0.002), and the V(110) (mean value 1.4% vs. 3.2%, p=0.006). However, the SDG is not statistically significantly different for either algorithm. Looking at the potential impact on skin acute reaction, although there is a significant reduction of V(110) using an inverse algorithm, it is unlikely this 1.6% volume reduction will present a significant clinical advantage over a forward algorithm. Both algorithms are equivalent in removing the hot spots on the inframammary fold, where acute skin reactions occur more frequently using a conventional wedge technique. Based on these results, we recommend that both forward and inverse algorithms should be considered for breast IMRT planning.

Algorithms↗

PubMed2005

How are hemoglobin levels affected by androgen deprivation in non-metastatic prostate cancer patients?

PURPOSE: To examine the change of hemoglobin in relation to testosterone level in non-metastatic prostate cancer patients receiving 2-year androgen suppression. METHODS AND MATERIALS: A cohort of 72 patients, as participants of a phase II study, were treated with adjuvant radiotherapy plus 2-year androgen suppression after surgery to reduce the risk of relapse. Patients had laboratory tests including hemoglobin (Hb) and testosterone, and a quality of life questionnaire at regular intervals during the androgen suppression and post-androgen suppression period. The pattern of the change in Hb was evaluated in relation to testosterone level. The clinical significance of Hb change was assessed with a correlation analysis between Hb and the three domains of the questionnaire (global health status, physical functioning, and fatigue). RESULTS: Median age was 64.2 years. Median follow-up was 37 months. Mean Hb at the baseline was 148.4 g/L. It declined slightly with radiotherapy by 2.2 g/L. Maximal Hb decline during androgen suppression was 10.5 g/L (p < 0.0001), occurring at 24 months after the initiation of androgen suppression. In most patients, Hb decline was < 20 g/L. In the post-androgen suppression period, the recovery of Hb was slow and followed that of testosterone. The three quality of life domains did not show any significant correlation with the change in Hb. CONCLUSION: The decline and recovery of Hb was closely related to that of testosterone. Two-year androgen suppression resulted in a statistically significant decline of Hb, which had, however, no clinically apparent adverse effect on the three quality of life domains.

Aged↗

PubMed2004

Technique for in-office cranial bone harvesting.

PURPOSE: This is a report of a technique of cranial bone harvesting suitable for the outpatient setting. MATERIALS AND METHODS: Bone scrapers are used for the harvesting of cranial bone shavings with the patient under intravenous sedation or general anesthesia. RESULTS: Graft volumes larger than that usually obtainable from intraoral sites and the tibia have been harvested utilizing this technique. In a series of 8 first patients, the largest volume of bone obtained was 14 cc with no complications related to the donor sites. These cases include the following types of pre-implant reconstructive procedures: large unilateral sinus grafting, bilateral sinus grafting/guided-bone regeneration of an entire alveolar ridge, inlay grafting of the alveolus, inlay grafting in association with distraction osteogenesis, subnasal grafting, alveolar cleft grafting, closure of large oroantral defects combined with sinus grafting, and grafting of an grossly atrophic mandible with simultaneous placement of dental implants via the submental approach. CONCLUSION: This is a safe bone harvesting technique providing an alternative source of autogenous bone graft.

Alveolar Ridge Augmentation↗