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Biomedical subjects

K B Chia

Publications and source records attributed to K B Chia.

At least 19 recordsLinked to original sources
PubMed1988

Radiotherapy of early glottic cancer Singapore, 1978-1981.

This study analyses the results of primary radiotherapy for 44 patients with early glottic cancer (Tis, T1 stage) given at the Therapeutic Radiology Department, Singapore General Hospital during the 4-year period from 1978 to 1981. Irradiation was delivered using cobalt teletherapy with free set-ups, and without "air-gap" compensation. Total doses of 55Gy to 64Gy were given in daily fractions of 1.8Gy, treating five times a week. The crude 5-year survival rate for Tis/T1a tumours was 88.9% and for T1b lesions, 81%. On correcting for deaths from intercurrent disease, the survival rates improved to 95.5% and 92.6% respectively. In 33 cases where the quality of voice after radiation was assessed, 15 patients (45.4%) retained good voice quality with an additional 11 patients (33.3%) having acceptable voice quality. In seven cases the voice after radiation was rated as poor. Nine patients had local recurrence, giving a rate of 20.4%. One other patient had cervical node metastasis and subsequently developed lung secondaries. Surgery, solely or with re-irradiation, was an effective treatment for local recurrence. Re-irradiation alone failed to control any case with recurrence.

Carcinoma, Squamous Cell↗
PubMed1988

Hyperthermia with radiotherapy.

The use of hyperthermia together with radiotherapy in the treatment of relatively radioresistant tumours has been widely studied. In this preliminary non control study we used a 8MHz RF capacitive heating machine together with temperature probes inserted into the tumours under local anaesthesia. 27 patients with advanced post-radiation tumour recurrences as well as known radioresistant tumours were selected for treatment with hyperthermia and radiation. 7 patients withdrew from the study because of their intolerance to heat. 3 patients received superficial skin burns. Of the 20 patients studied, we were able to obtain moderate hyperthermia in most cases. 2 patients showed complete responses and 13 partial responses, giving rise to a total response rate of 75%. Some of the technical difficulties in achieving satisfactory hyperthermia are discussed. These include insertion of multiple probes into the body and the problem of achieving uniform heating of the tumour. Advances in hyperthermia can be expected with the development of improved methods of heat delivery and temperature measurements. However, presently methods of heat delivery can be improved by careful adjustment of the heating applicators and manipulation of cooling pads to avoid areas of excessive heating. Further clinical trials should be carried out to establish the optimum technique of hyperthermia.

Adult↗
PubMed1987

Advanced colorectal carcinoma--5 year survival of 76 cases treated at the Department of Therapeutic Radiology, Singapore General Hospital.

The results of 76 cases of advanced colorectal carcinoma treated at the Department of Therapeutic Radiology, Singapore General Hospital, from 1977 to 1978, are presented. All cases had "Curative" Surgery and were given adjuvant radiotherapy or chemotherapy or both. All were adenocarcinoma and had lymph node involvement as well as tumour infiltration through the bowel wall. 44 cases of rectal carcinoma were given radiotherapy to the pelvis followed by I/V 5-fluorouracil for at least one year. 32 cases of colon cancer were given I/V 5-fluorouracil for at least one year. 20 of these cases had cancer of the sigmoid colon and were given pelvic irradiation as well. The five year actuarial survival rates were 27.8% for rectal cancer and 24.3% for colon cancer.

Actuarial Analysis↗
PubMed1985

Radiotherapy of carcinoma of the uterine cervix in Singapore, 1973-1975.

The results of 322 patients with uterine cervix carcinoma treated by radiotherapy at the Singapore General Hospital in the 3-year period from 1973 to 75 are presented. Two hundred seventy-nine patients were treated with a combination of intracavitary radium, using Fletcher-Suit applicators and cobalt teletherapy; the remaining 43 patients received only cobalt teletherapy. One hundred thirty-four patients (41.6%) presented with FIGO Stage III disease. Only 46 patients (14.3%) presented with Stage I disease, showing that patients tended to present late in the disease course. Five-year actuarial (uncorrected) survival rates of 86.7% for Stage I, 65.0% for Stage II, 41.4% for Stage III and 4.9% for Stage IV were obtained with corresponding 10 year rates of 79.6%, 60.2%, 35.2% and 0%. The overall 5 and 10 year survival rates were 54.0% and 48.2%, respectively. The survival rates "flattened off" at about 7-8 years, reflecting late deaths after the fifth anniversary of treatment. Non-severe complications consisted mainly of chronic proctitis (41.3%) and vaginal stenosis (20.8%). Major complications were intestinal stricture (1.2%) and fistula formation (1.6%).

Adult↗
PubMed1983

HLA and nasopharyngeal carcinoma in Chinese--a further study.

This paper reports the results of 8 years of HLA typing of newly diagnosed nasopharyngeal carcinoma (NPC) patients among Chinese in Singapore, and compares the HLA profile of NPC cases with that of the normal Chinese population. Earlier results had indicated an association with A2 and BW46, but the heterogeneity of the earlier case series, which contained a proportion of long-term survivors, obscured other aspects of the relationship. In this paper, the risk associated with A2 (relative risk = 1.5) and BW46 (relative risk = 1.9) is confirmed, showing a much higher relative risk in the presence of both antigens, and a risk is also demonstrated for B17 (relative risk = 2.1). Relative risks of less than unity are observed for AII (relative risk = 0.5) and B13 (relative risk = 0.5). Data from family studies indicate the importance of the haplotype A2.BW46 in determining risk for NPC.

Adult↗
PubMed1983

Teratoid carcinosarcoma of the paranasal sinuses.

Malignant tumours with teratoid or blastomatous features are exceptionally rare in the upper respiratory tract with only 8 documented cases, including the 3 in this report. The tumours occurred in adults aged 27 to 62 yr, and the sites of origin were the ethmoid sinus (4 cases), ethmoid and other paranasal sinuses (2 cases), unspecified sinuses (1 case) and nasopharynx (1 case). The disease was rapidly fatal in 3 cases in which treatment was restricted to surgery and was associated with longer survivals in those given supportive radiotherapy. The tumours are locally aggressive and may invade soft tissues, bone, orbit and cranial cavity. Histologically, the tumours are characterized by a mixture of epithelial and mesenchymal components including cellular elements with immature or embryonal characteristics. These tumours, variously termed malignant teratoma, blastoma, teratocarcinoma or teratoid carcinosarcoma, probably comprise a homogeneous group of neoplasms since their histological and biological features are essentially similar. It is postulated that the tumours develop from primitive embryonic tissues or pluripotential cells that have remained sequestered in the sinonasal tract.

Adult↗
PubMed1982

The development of radiation therapy in Singapore--its present status & future prospects.

X-rays were introduced into Singapore soon after their discovery but their use in therapy did not take place until 1914. Radiation therapy was widely used only after 1949 when the first deep X-ray machine was installed. Since then the number of patients given this treatment has progressively increased, keeping pace with the rising cancer incidence. In 1981, 2533 cases were referred for treatment, out of which 1889 were given radiation treatment. The value of radiotherapy in malignant disease has been established both as a palliative as well as a radical method of treatment. Through improved techniques, better therapy equipment, and greater understanding of malignant disease, results of radical radiotherapy have shown progressive improvement. Further advances can be expected with newer techniques which have been put to clinical trials recently. These are planning with CT Scan, conformation radiotherapy, radiation sensitizers and protectors, hyperfractionation, hyperthermia, intraoperative radiotherapy, heavy particle radiotherapy and isotopic immunoglobulin therapy.

Forecasting↗
PubMed1981

Radiation induced cancer: a report of 10 cases.

Ionizing radiations have been shown to be carcinogenic to man as well as experimental animals. Malignancies following therapeutic radiation occur rarely. Over the past 10 years the authors recorded 10 cases of tumours in irradiated tissues. 3 occurred in patients irradiated for nasopharyngeal carcinoma, 3 were irradiated for tuberculosis adenitis, 2 for carcinoma of the cervix, 1 for carcinoma of the breast and 1 for basal cell carcinoma. The latent period for tumour induction following the irradiation varied from 5 years to 31 years. All these cases showed no evidence of recurrence or metastases of the original primary lesion; and the histology of the second primary differed from the first. Evidence of radiation damage was seen in all cases except for 2 patients who were treated for tuberculosis adenitis. The doses received varied from 900r to about, 9000r. Among the tumours produced, there were 3 cases of squamous cell carcinoma of the oral & postcricoid region, 2 cases of papillary carcinoma of the thyroid, 2 cases of adenocarcinoma of the rectum, 1 case of adenocarcinoma of the ethmoid, 1 case of osteosarcoma of the mandible and 1 case of extraskeletal osteosarcoma. The clinical features of these cases are discussed and other cases reported in the literature are reviewed.

Adenocarcinoma↗
PubMed1981

Adjuvant combination chemotherapy for osteosarcoma.

The management of patients with osteosarcoma in Singapore has for many years been an unrewarding task for the attending physicians. Encouraged by reports of long-term survivals with adjuvant cytotoxic chemotherapy appearing in 1975, orthopaedic surgeons and radiation therapists at the Singapore General Hospital undertook a program of combination chemotherapy in moderate doses for osteosarcoma patients with localised disease treated by ablative surgery. A few who refused surgery had irradiation of the primary tumour.

Adolescent↗
PubMed1981

Hyperthermia.

Heat was known to have a beneficial effect on malignancies. Fevers resulting in temperature of 41 degrees C have been known to cause tumours to regress. Hyperthermia per se has been shown experimentally to be effective in some cancers. The method of achieving hyperthermia (whole body, regional and local) and the measurements of temperatures with different probes are discussed. Preliminary results indicate that hyperthermia combined with ionising radiations and cytotoxic drugs show great promise.

Bacterial Toxins↗
PubMed1981

A report of 21 cases of malignant lymphoma treated by radiotherapy.

In 1971, 21 new patients with malignant lymphoma were treated at the Therapeutic Radiology Department, Singapore General Hospital. 17 patients completed their courses of radiotherapy. Of the 17 patients given radical treatment, 5 were of Hodgkin's disease and 12 of Non-Hodgkin's disease. The 5-year survival for the group with Hodgkin's disease is 80% (4/5). The 5-year survival for the group with Non-Hodgkin's disease in 41.6% (5/12).

Adolescent↗
PubMed1980

Radiotherapy in treatment of nasopharyngeal carcinoma.

Nasopharyngeal Carcinoma is one of the most prevalent malignancies treated by radiotherapy in Singapore. Planning of the radiation fields for this condition is difficult because of the proximity of anatomical structures that are vulnerable to irradiation, such as the eyes, brain stem and cervical cord. However, the treatment results have shown progressive improvement. The treatment technique currently used utilized cobalt as well as caesium teletherapy units. Of the 104 cases treated in 1970 using this technique, the overall absolute 5 years survival rate with no evidence of disease is 30.8%. For Stage I cases, the rate is 62.5%. The prognosis is significantly better for the female than the male and is also related to age.

Adolescent↗
PubMed1978

Distant metastases in nasopharyngeal carcinoma.

Three hundred and fifty-two consecutive cases of nasopharyngeal carcinoma were analysed to determine the pattern of distant metastases. Diagnosis of distant metastases was made wholly on clinical signs and radiography. Ninety-nine patients developed distant metastases, an incidence rate of 28.1%. There did not appear to be any difference in "risk" by age or sex. The predilection of this cancer to develop skeletal metastases is further confirmed. Pulmonary and hepatic involvement were the next commonest. Both extent of primary tumour (T) and cervical lymph node status (N) exerted a significant influence on the probability of metastases developing. Thus significant differences in metastatic rate were observed between T0/T1, T2 and T3/T4 and N0, N1, N2 and N3 groups. 65.6% of metastatic cases had control of local disease (nasopharynx and cervical lymph nodes). When metastases are diagnosed the prognosis is gloomy with a median survival under four months and a fatality rate of 91% within a year of first metastasis.

Adolescent↗