Tsz-Kok Yau

MAJOR LATE TOXICITIES AFTER CONFORMAL RADIOTHERAPY FOR NASOPHARYNGEAL CARCINOMA-PATIENT-AND TREATMENT-RELATED RISK FACTORS

PURPOSE To retrospectively analyze the factors affecting late toxicity for nasopharyngeal carcinoma. METHODS AND MATERIALS Between 1998 and 2003, 422 patients were treated with a conformal technique with 2-Gy daily fractions to a total dose of 70 Gy. Conventional fractionation (5 fractions weekly) was used in 232 patients and accelerated fractionation (6 fractions weekly) in 190 patients. One hundred seventy-one patients were treated with the basic radiotherapy course alone (Group 1), 55 patients had an additional boost of 5 Gy in 2 fractions (Group 2), and 196 patients underwent concurrent cisplatin-based chemotherapy (Group 3). RESULTS The 5-year overall toxicity rate was significantly greater in Group 3 than in Group 1 (37% vs. 27%, p = 0.009). Although the overall rate in Group 2 was not elevated (28% vs. 27%, p = 0.697), a significant increase in temporal lobe necrosis was observed (4.8% vs. 0%, p = 0.015). Multivariate analyses showed that age and concurrent chemotherapy were significant factors. The hazard ratio of overall toxicity attributed to chemotherapy was 1.99 (95% confidence interval, 1.32-2.99, p = 0.001). The mean radiation dose to the cochlea was another significant factor affecting deafness, with a hazard ratio of 1.03 (95% confidence interval, 1.01-1.05, p = 0.005) per 1-Gy increase. The cochlea that received >50 Gy had a significantly greater deaf rate (Group 1, 18% vs. 7%; and Group 3, 22% vs. 14%). CONCLUSION The therapeutic margin for nasopharyngeal carcinoma is extremely narrow, and a significant increase in brain necrosis could result from dose escalation. The significant factors affecting the risk of deafness included age, concurrent chemoradiotherapy, and greater radiation dose to the cochlea.

Screening for family members of patients with nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is well known for its peculiarly skewed distribution with highest incidence in Southern Chinese population. Familial aggregation is evident, hence screening for early detection is offered by oncology centers in Hong Kong to first‐degree relatives of patients with NPC. During the period 1994–2001, 929 family members were screened in our center. The screenees were advised to attend an annual examination that includes serological test against Epstein Barr Virus (EBV), physical examination to exclude cervical lymphadenopathy and cranial nerve palsy, and endoscopic examination of the nasopharyngeal region. Two different methods were used for the serology test: indirect immuno‐fluorescent (IF) test for IgA against viral capsid antigen; and starting in 1997 enzyme‐linked immunosorbent assay (ELIZA) against nuclear antigen and viral capsid antigen. Twelve cases of nasopharyngeal carcinoma were diagnosed, giving a detection rate of 5/1,155 (433/100,000) person‐year for male and 7/1,404 (499/100,000) person‐year for female participants observed. The corresponding average annual incidence in Hong Kong during this period was 24.1 and 9.6 per 100,000, respectively. Forty‐one percent of these detected cases had Stage I disease, whereas only 2% of patients referred to the department for primary treatment presented with such early disease. Six cases were detected at first visit, and all were EBV‐positive. Another 78 screenees with positive serology at first visit were followed up for 204 person years, and thus far NPC was detected in 3 after an interval of 6–32 months. Of the 845 initially EBV‐negative screenees followed up for 2,337 person‐years, NPC was detected in 3 after an interval of 12–45 months. One showed sero‐conversion at the time of diagnosis. We conclude that family members of known patients do show a substantially higher risk of developing NPC, and regular screening by current method improves the chance of early detection.

RapidArc radiotherapy planning for prostate cancer: Single-arc and double-arc techniques vs. intensity-modulated radiotherapy

RapidArc is a novel technique using arc radiotherapy aiming to achieve intensity-modulated radiotherapy (IMRT)-quality radiotherapy plans with shorter treatment time. This study compared the dosimetric quality and treatment efficiency of single-arc (SA) vs. double-arc (DA) and IMRT in the treatment of prostate cancer. Fourteen patients were included in the analysis. The planning target volume (PTV), which contained the prostate gland and proximal seminal vesicles, received 76 Gy in 38 fractions. Seven-field IMRT, SA, and DA plans were generated for each patient. Dosimetric quality in terms of the minimum PTV dose, PTV hotspot, inhomogeneity, and conformity index; and sparing of rectum, bladder, and femoral heads as measured by V70, V-40, and V20 (% of volume receiving >70 Gy, 40 Gy, and 20 Gy, respectively), treatment efficiency as assessed by monitor units (MU) and treatment time were compared. All plan objectives were met satisfactorily by all techniques. DA achieved the best dosimetric quality with the highest minimum PTV dose, lowest hotspot, and the best homogeneity and conformity. It was also more efficient than IMRT. SA achieved the highest treatment efficiency with the lowest MU and shortest treatment time. The mean treatment time for a 2-Gy fraction was 4.80 min, 2.78 min, and 1.30 min for IMRT, DA, and SA, respectively. However, SA also resulted in the highest rectal dose. DA could improve target volume coverage and reduce treatment time and MU while maintaining equivalent normal tissue sparing when compared with IMRT. SA achieved the greatest treatment efficiency but with the highest rectal dose, which was nonetheless within tolerable limits. For busy units with high patient throughput, SA could be an acceptable option.

Trends and patterns of breast conservation treatment in Hong Kong: 1994-2007.

PURPOSE Breast conservation treatment (BCT) was quite unpopular in Hong Kong until the early 1990s, but the trends and patterns of BCT use in the past 14 years have not been studied since. The purpose of this study was to identify the latest trends and patterns. METHODS AND MATERIALS All consecutive cases of female breast cancer referred to a community oncology center in Hong Kong between 1994 and 2007 were retrospectively reviewed. Of the 2,375 women with T1-2 invasive breast cancer who underwent surgery, 1,137 (48%) had T1 (</=2 cm) disease and 1,238 (52%) had T2 (>2 cm-</=5 cm) disease. Median patient age was 51 years (range, 24-95 years); 65% patients had their surgery in public hospitals. RESULTS Of the total patient cohort, 2,153 (91%) patients presented with palpable breast masses and only 104 (4%) with mammographically detected cancers. Overall, 721 (30%) and 1,654 (70%) patients underwent BCT and mastectomy, respectively. There was no significant increase in the BCT rates (31%, SD 5%; p = 0.804) or mammographic detection rates (5%, SD 1%; p = 0.125) in Hong Kong between 1994 and 2007. In multivariate analyses, age </=50 years (OR 2.479; p < 0.001), mammographically detected tumors (OR 1.868; p = 0.007), T1 tumors (OR 3.159; p < 0.001), surgeries in private hospitals (OR 1.288; p = 0.018), and negative nodal status (OR 1.886; p < 0.001) were independent factors predictive of a higher likelihood of a woman having BCT. CONCLUSIONS Our results indicate a satisfactory acceptance of BCT by patients who are young and have small tumors, node-negative disease, or surgery in private hospitals. However, the continuing unpopularity of breast screening is likely a major factor limiting the broad use of BCT.

Toxicity of docetaxel plus cyclophosphamide as adjuvant therapy for breast cancer in Chinese patients – the Hong Kong experience

Aims:  The docetaxel and cyclophosphamide (TC) regimen is increasingly popular as adjuvant chemotherapy for operable breast cancers. We conducted a retrospective study in Hong Kong to evaluate the toxicity of this regimen in Chinese patients.

Ductal carcinoma in situ of breast: detection and treatment pattern in Hong Kong

INTRODUCTION The treatment of ductal carcinoma in situ has been widely reported in the western and other Asian countries, but the relevant data in Hong Kong are relatively limited. This study aimed to evaluate the latest detection and treatment pattern for ductal carcinoma in situ in Hong Kong so as to guide planning of future service provision. METHODS This was a retrospective case series study. A total of 573 patients who registered with the Hong Kong Breast Cancer Registry, and were diagnosed and treated in Hong Kong from January 2001 to December 2011 were reviewed. RESULTS Compared with invasive breast cancer patients, patients with ductal carcinoma in situ were younger (median, 48.6 vs 50.3 years; P<0.001), had a higher education level (P<0.001), had a higher total monthly family income (P<0.001), and more common breast-screening habits (P<0.001). Significantly more patients with ductal carcinoma in situ underwent breast-conserving surgery than their invasive cancer counterparts (55.8% vs 36.7%; P<0.001). The percentage of screen-detected ductal carcinoma in situ was relatively lower than that reported in other studies, but was still much higher than that in invasive breast cancer patients (29.0% vs 4.7%; P<0.001). Screen-detected patients with ductal carcinoma in situ tended to choose a private hospital instead of a public hospital for treatment (P=0.05) and to undergo breast-conserving surgery (P=0.02). With a median follow-up of 3 years, the crude local recurrence rate after mastectomy and breast-conserving surgery was 0.4% and 3.3%, respectively; 44% of recurrent tumours had developed invasive components. No regional recurrence, distant recurrence, or cancer-related deaths were recorded. CONCLUSIONS In the absence of a population-based breast screening programme in Hong Kong, ductal carcinoma in situ is more frequently found in the higher social classes and managed in the private sector. The clinical outcome of ductal carcinoma in situ is excellent and more than half of the patients can be successfully managed with breast-conserving surgery.