Synchronously performed prostatic fine needle aspiration and core biopsies--an appraisal.

GG Prabhu, MS Rao, N Venugopal 
 Dept of Urology, Kasturba Medical College and Hospital, Manipal, Karnataka.

Correspondence Address:
G G Prabhu
Dept of Urology, Kasturba Medical College and Hospital, Manipal, Karnataka.

Full Text

::   Introduction

The standard method of obtaining tissue for diagnosis of prostatic cancer was large core needle biopsy until fine needle aspiration (FNA) cytology became available. Initial enthusiasm in this simple and speedy method of diagnosis led to its wide use. As experience in this relatively new technique accumulated and cytomorphological interpretation difficulties were realised[1] especially when equivocal reports needed confirmation by traditional core biopsies, the trend seems to have reshifted towards employing core biopsy once again to diagnose prostatic cancer. This is especially true after the advent of the biopsy device, which uses an automatic spring loaded 18 gauge needle. The thin needle provides a slender core of solid tissue that can be accorded standard histologic evaluation including tumour grading. It reduces the former need for a specially skilled biopsy technique by a trained cytopathologist[2].

In order to work out strategy in the prevailing organisational set-up of our institution, the various aspects of FNA and core biopsies, done either singly or in combination on 126 patients, were reviewed. The diagnostic potential and the cost benefits of the two sampling methodologies both singly as well as in combination were studied.

::   Methods

The duration of study was 5 years. Hundred and twenty-six patients who underwent digitally guided transrectal prostatic FNA and core biopsy, either singly or in combination, were categorised into three groups, Group I consisted of patients who underwent only core biopsy (n = 45), Group II who underwent only fine needle aspiration (n = 23) and Group III (n = 58) who were subjected to both the methods simultaneously, from the same area of the prostate. Biopsy was performed when clinical (digital rectal examination), radiological (osteoblastic lesions) and biochemical (successive confirmation of elevated acid phosphatase levels) findings either in isolation or in combination suggested prostatic rnalignancy. Digital rectal examination was done by at least two clinicians and biopsy was performed even when one of them felt the need for it.

Sampling by both biopsy techniques was done by resident doctors at varying experience levels in their course.

All biopsies be it fine needle or core, were performed without anaesthesia, under the cover of a single dose antibiotic." Biopty gun" was acquired and introduced for core biopsy in the latter part of the study. For FNA biopsy 21 G lumbar puncture needle in conjunction with a 10 ml syringe was used. Smears made on glass slides were air-dried and fixed in ethanol.

::   Results

The three groups of patients were subdivided, depending on the pathologists' report into four subgroups viz a) benign, b) suspicious of malignancy, c) malignant and d) inadequate sampling or no prostatic tissue. Results are shown in [Table:1].

When done together, FNA and core biopsy, with tour subgroups depending on pathologists' report, makes for 16 possible combinations of which 12 were encountered in our series. [Table:2].

Repeat biopsy was resorted to when sampling was inadequate or equivocal by both methods singly or in combination. In Group I, 8 patients, in Group II 9 and in Group III 2 patients had to be rebiopsied. While there was not a single instance of an equivocal report in Group I, one patient each in Group II and Group III had to be rebiopsied as the material sampled presented features only suspicious of malignancy.

Only in Group III (who were subjected to both the methods of sampling), 2 patients had transient fever; 4 had bleeding in the form of temporary mild haematuria, 1 developed mild bleeding per rectum and 2 had both urinary and rectal bleeding not requiring major measures for control.

There was no control on detection of tumour tracking as we have definitively treated all proven cases of prostatic cancers. Nevertheless, on careful follow-up, clinically there was no evidence of this complication

::   Discussion

The selection of biopsy technique for diagnosing prostatic malignancy at any centre depends upon its availability and familiarity to all concerned with sampling technique as well as interpretation while in the past, when fine needle aspiration was still in its infancy, core biopsy had reigned as the standard biopsy technique. Recently reports of digitally guided biopsies suggest that cytologic evaluation is as sensitive as histologic evaluation[3],[4].

A single physician examining the patient, performing the aspiration and reading the slide is the organisational arrangement in Scandinavian countries. The impressive sensitivity rates achieved by these "clinical hybrids" by virtue of such total involvement may not be attainable at centres where there are many people involved at various stages of sampling and interpretation[5]. Other European clinicians, who had to avail of pathology services, adopted FNA earlier because it provided a much needed method of efficient diagnosis[6]. Though expertise in the sampling technique is ideal, at most of the centres in India it is hard to find a full time uro-pathologist or oncopathologist dealing exclusively with uro-cytology or histopathology. In our Institute also, it is not possible to have a single person dedicated to performing biopsy procedures. As a training institute, universal training has to be given to all medical residents and secondly organisation cannot afford personnel exclusively engaged in all phases. The pathology department of our hospital also cannot spare a person solely for performance of prostatic or other biopsies, preparation of material and sample examinations. Hence in the present study also numbers of residents with varying seniority and experience have contributed. In a comparative evalupfion of FNA and corebiopsy, the rate of cancer diagnosis was 53% with cytologic evaluation and 54% with histologic evaluation and an improved combined yield of 61 %, even at a centre in the United States[7].

In the present study, although comparable strike rates could be achieved by both FNA (72.83 %) and core biopsy (79.61 %), there was an overall high rate of inadequate sampling, 20.38% for FNA and 27.16 % for core biopsy. This was accepted in our hospital setting owing to factors like involvement of trainees with varying experiences, uncooperative patients in a few instances who interfere with satisfactory sampling and introduction of improved instrumentation technique (i.e., Biopty needle) in the latter part of this study.

Whenever both the sampling techniques were employed in combination (despite a high negative strike rate for each), the diagnostic inadequacy of one was found to be compensated for by the other thereby bringing down the rebiopsy rate in Group III (two patients). This is very reassuring in a setting with training concerns. On the other hand, 8 patients from Group I and 9 from Group II had to undergo repeat biopsies on account of inadequate sampling. This had naturally prolonged their stay in the hospital adding to the overall costs,

The benefit of using both techniques together in the same patient was the time saved in giving therapy in both benign hypertrophy and carcinoma cases. The FNA report is available in 48 hrs in our hospital whereas the core biopsy report takes 5-7 days time. Though the combined cost of these techniques was higher than that of individual, there was a significant reduction in hospital stay. In case the FNA report was inadequate or suspicious one obtained biopsy report within next 3-5 days without a need to prolong hospital stay. Thus in the long run this arrangement is cost beneficial. Also it helped to overcome other organisational inconveniences in our multi-observer set-up where the patients needs to be often institutionalised between the biopsy and therapy owing to the distant location of this centre.

Admittedly, the pain and discomfort caused by multiple needle passes as in Group III may make a patient withdraw during multiple biopsies which may lead to inadequate sampling. Further, in Group I, the percentage gain for benign and malignant lesions was higher than in Group II and Group III, suggesting a superior diagnostic potential for core biopsy. Inadequate sampling was minimum in Group II giving fine needle aspiration a status of rapidly interpretable sampling strategy.

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