Conservative treatment for low rectal carcinoma by local excision with or without radiotherapy

Thirty-seven patients with low rectal carcinoma were treated by transanal resection between January 1979 and December 1988. Adjuvant radiotherapy was used in eight patients before operation, in 13 after operation and six patients had both preoperative and postoperative radiotherapy. The selection criteria for transanal resection were low, superficial tumours treated conservatively with curative intent (group 1, 18 patients) or patients medically unfit for (12) or refusing (seven) abdominoperineal resection (APR) (group 2, 19 patients). In group 1, the local recurrence rate was 11 per cent with an overall 5-year survival rate of 100 per cent. In group 2, the local recurrence rate was 53 per cent with an overall 5-year survival rate of 35 per cent. There was no postoperative mortality and minimal morbidity. Salvage of local failure was by APR in six patients. The survival rate after local recurrence was 70 per cent at 1 year and 30 per cent at 5 years. Transanal resection can be proposed as a curative procedure for selected low, small, minimally infiltrating and well differentiated adenocarcinomas. Local control might be improved by postoperative radiotherapy for Astler-Coller stage B1 tumours or those above 3 cm in diameter. Further trials should examine the results of high-dose (60 Gy) preoperative radiotherapy so that transanal resection might be employed for favourable post-irradiation stage (0 or A) lesions. This new strategy will benefit from a better evaluation of tumour response after primary radiotherapy and an improved assessment of histological excision margins.

Direct reverse transcription--polymerase chain reaction from whole blood without RNA extraction

A simple, fast, efficient method of direct reverse transcription-polymerase chain reaction (RT-PCR) from whole blood without RNA extraction is described. After the erythrocytes in a few microliters of fresh blood were destroyed and removed, the total RNA was released from the leukocytes by means of water treated with diethyl pyrocarbonate. The solution was used as RNA template and directly introduced in the RT-PCR. Following this method, which is called direct RT-PCR, three different cDNA fragments were successfully amplified with three different pairs of primers, respectively. Meanwhile, the direct RT-PCR was compared with the RT-PCR from the extracted total RNA template. The results showed no obvious difference.

Age, dietary selenium and quantity of 7,12-dimethylbenz(a)anthracene influence the in vivo occurrence of rat mammary DNA adducts

The present studies determined the impact of age, dietary selenium and 7,12-dimethylbenz(a)anthracene (DMBA) dosage on the occurrence of DMBA-DNA adducts in rat mammary tissue. Diets formulated to contain selenium, as sodium selenite, at 0.1 (control) or 2.0 mg/kg were fed for 2 wk before DMBA treatment. Food intake and weight gain were not influenced by selenium intake. Anti- and syn-dihydrodiol epoxide adducts reached maximum binding by 24 and 36 h, respectively, after treatment with DMBA. Consumption of the diet containing 2.0 mg Se/kg inhibited the appearance of both anti- and syn-adducts by approximately 50% compared with controls. The occurrence of DMBA-DNA adducts correlated with a dosage of DMBA from 5 to 50 mg/kg body wt (r greater than or equal to 0.95). The ability of supplemental selenite to lower DMBA binding to mammary cell DNA increased as the quantity of the carcinogen administered increased. DMBA-DNA binding was found to increase with the increasing age of the rat. Nevertheless, dietary selenium supplementation was effective in reducing DMBA binding to DNA in all ages examined. These data confirmed the ability of dietary selenium to inhibit the in vivo metabolism of DMBA under a variety of conditions.

Inhibition of 7,12-dimethylbenz(a)anthracene-induced mammary tumors and DNA adducts by dietary selenite

The present studies were designed to examine the influence of dietary selenite supplementation on the initiation phase of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinogenesis and to correlate selenite-induced changes in the binding of DMBA metabolites to rat mammary cell DNA with the ultimate tumor incidence. Diets formulated to contain selenium, as sodium selenite at 0.1, 0.5, 1, 2, or 4 micrograms/g were fed for 2 weeks prior to and 2 weeks following treatment with DMBA (5 mg/kg body weight). Food intake and weight gain did not differ among treatments. Tumor incidence correlated inversely to the quantity of selenium consumed (r = -0.99). Final tumor incidences were 52, 32, 24, 14, and 10% for rats fed 0.1, 0.5, 1, and 4 micrograms selenium/g, respectively. In a separate group of rats fed a diet containing 4 micrograms selenium/g during both the initiation and promotion stages the final tumor incidence was 4.8%. Selenite supplementation for 2 weeks markedly depressed the occurrence of individual and total DMBA-DNA adducts. The final mammary tumor incidence correlated positively with total DMBA-DNA adducts (r = 0.99). These studies clearly demonstrate that selenite can inhibit the initiation stage of mammary carcinogenesis. This reduction in tumor incidence is likely due to a reduction in carcinogen metabolism and ultimately adduct formation.