104 which should not go unchallenged. He claims that the results of treatment of early stomach cancer are not very encouraging and that it is unknown whether earlier detection can produce a worth-while increase in long-term survival. Figures are available from nine cooperating institutions in Japan1 which show that the five-year survival-rate from early gastric cancer (i.e., cancer limited to the mucosa or submucosa) is 95-5% in a group of 330 patients. Figures of 94% five-year survival in this group of patients are reported from the Aichi Cancer Research Institute, Nagoya, Japan. In several Japanese hospitals, early gastric cancer accounts for 30% of all gastric cancer cases seen, whereas in the United Kingdom it is less than 1 %. In Britain more than 95% of all patients with stomach cancer will die of this disease. We believe that this figure is Such unsupported statements as unacceptably high. Professor Hobbs has made (which are indeed contrary to the published reports from Japan) can do nothing but contribute further to the possibly unwarranted pessimism about stomach cancer. Llandough Hospital, Penarth, Glamorgan CF6 1XX.

D. M. D. EVANS J. L. CRAVEN.

BOWIE AND DICK TEST FOR AUTOCLAVES

SIR,-Dr Morris and Mr Everall (Dec. 7, p. 1382) draw attention to conflicting results, obtained from different rolls of 3M Autoclave tape no. 1222 in the routine performance of the Bowie and Dick autoclave tape test. Without first examining the test sheets in question, it is impossible to make specific comment; we have, however, never disputed that in marginal cases it may well be difficult to distinguish between a pass or a fail with this test. Neither have we contended that individual rolls of tape are without variation. These exist, as with all manufactured items, but we are satisfied that they are no greater now than when the Bowie and Dick tape test was first introduced. What is unquestionably true is that poor or inadequate storage conditions can have an adverse effect upon the performance of the tape. We have always called for effective stock control and stock rotation of our product, and for storage in a clean, dry environment. Indeed our outer packaging states precisely: 1. store in a cool dry place; 2. avoid prolonged exposure to strong sunlight. We are in complete agreement with the recommendations calling for the clear identification of individual rolls by means of a core stamp, and we are happy to confirm that such a system is in the course of implementation with the approval of the Department of Health and Social Secu-

rity. 3M United Kingdom 3M House,

Limited,

Wigmore Street, London W1A 1ET.

J. GASTON, Sales Manager, Medical Services, Health Care Products Division.

MODIFIED BOWIE-DICK TEST

SIR,-The National Health Institute of the New Zealand Department of Health has, for a number of years, recognised the limitations associated with the use of the BowieDick test. Our programme of the physical testing of sterilisers in hospitals using thermocouples has detected mechanical faults that have influenced the temperature in the load item during the so-called sterilisation cycle. In our experience, the routine use of the Bowie-Dick test has failed to indicate the true conditions of time at a temperature and can only give an indication of uniform treatment at an unspecified temperature. 1.

Kidokoro, T. Ganu Monograph Baltimore, 1971.

on

Cancer Research No. 11, p. 45.

Because temperature and the presence of moisture are the primary requirements, the Department of Health advised New Zealand hospitals in November, 1970, to use the Diack Steriliser Control (121 C) and the VAC Steriliser Control (132 C) in conjunction with other indicators such as the 3M Tape. When a fault develops in a steriliser, the most serious effect will be when the anticipated temperature within the load item is not realised. For this reason, we agree with Robert F. Smith (June 29, p. 1349). National Health Institute, Department of Health, Wellington, New Zealand.

J. R. REID A. P. DIXON.

NITROBLUE-TETRAZOLIUM TESTS

SIR,-We were interested in the article (Nov. 23, p. 1248) by Dr Segal on the nitroblue-tetrazolium (N.B.T.) test. We do not intend to comment on the sections concerned with the N.B.T. test as a physiological test of neutrophil function, but, having completed over 7000 N.B.T. tests in the investigation of bacterial infection, we feel qualified to challenge his dismissal of the use of the N.B.T. test as an aid to clinical diagnosis. We should like to comment on three aspects. Firstly, it should be apparent from Dr Segal’s article that there is no such thing as the N.B.T. test. The number of variations of technique which have been used is bewildering and unhelpful. Park’s original contention was that useful discrimination between (bacterially) infected patients and patients free of infection could be achieved by using the technique which he devised.1 Numerous papers have followed, many using a variation of the technique,2-4 and have either confirmed or denied this original assertion, often on small numbers of patients, and taking the normal range as the range described in the early papers.2 If any investigator modifies a technique, he surely owes it to the technique, his patients, and to the scientific method to compare formally the two techniques and to establish a normal range for the modified technique on a large series of controls. Several investigators have incorporated into their modified techniques factors which make comparisons with the original test extremely difficult. 2-4 To give a

simple example, which we can confirm, the concentration of heparin has recently been shown to have a profound effect on the result of the test.5 How many of those who condemned the N.B.T. test, controlled this factor carefully ? We have always adhered to Park’s technique exactly, 6 apart from a staining modification which has no effect on the test value. We propose to refer to our technique as Park’s (N.B.T.) test, since, although we dislike eponyms, we wish it to be quite clear that this is our technique. Secondly, we have found from training other people to perform the test that reading of the result is a very variable factor, even to the extent of a positive result being converted to a negative result and vice versa, when compared with the reading of an experienced observer. Reading became more and more accurate and comparable over a period of several weeks. Most of the errors were due to those factors which 7 we detailed in an earlier report. Thirdly, we have always been disappointed at the failure of some authors to appreciate that assessing the N.B.T. test requires a very high standard of bacteriological work, to ensure that the results against which the N.B.T. test results are being viewed are beyond criticism. To give two simple 1. 2. 3. 4. 5. 6. 7.

Park, B. H., Fikrig, S. M., Smithwick, E. M. Lancet, 1968, ii, 532. Steigbigel, R. T., Johnson, P. K., Remington, J. S. New Engl. J. Med. 1974, 290, 235. Segal, A. W., Trustey, Sheila F., Levi, A. J. Lancet, 1973, ii, 879. Drysdale, H. C. ibid. 1972, ii, 1198. Hohn, D. C., Lehrer, R. I. Infect. Immun. 1974, 10, 772. Freeman, R., King, B. Lancet, 1971, ii, 1154. Freeman, R., King, B. J. clin. Path. 1972, 25, 912.

Letter: Bowie and Dick test for autoclaves.

104 which should not go unchallenged. He claims that the results of treatment of early stomach cancer are not very encouraging and that it is unknown...
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