Cost effectiveness of a fine needle aspiration clinic

The use of diagnostic patterns for interventional cytopathology during rapid on-site evaluation and final classification

Pathologist-performed fine-needle aspiration, or interventional cytopathology, is a minimally invasive, highly accurate technique for sampling and diagnosing palpable lesions. Utilizing cytomorphologic patterns during rapid onsite evaluation (ROSE) and final classification is one of many strategies that an interventional cytopathologist can employ to simplify the diagnostic approach. Herein, we provide an overview of the salient cytomorphologic patterns encountered in common specimens obtained by the interventional cytopathologist, including major salivary glands, the thyroid gland, and superficial lymph nodes. The topics covered should provide a primer for those interested in utilizing a site-specific, pattern-based approach to cytopathologic evaluation. In summary, cytomorphologic patterns can be used during ROSE to establish adequacy, build a differential diagnosis, and to appropriately triage the specimen for additional investigation, such as microbiology cultures, a liquid-based preparation, a cell block preparation, flow cytometry, chemical analysis, or molecular diagnostic tests. Finally, this approach can be applied at the time of diagnosis to suggest additional ancillary studies, such as immunohistochemistry, and to inform accurate and definitive classification.

Basics of cytology

This overview is intended to give a general outline about the basics of Cytopathology. This is a field that is gaining tremendous momentum all over the world due to its speed, accuracy and cost effectiveness. This review will include a brief description about the history of cytology from its inception followed by recent developments. Discussion about the different types of specimens, whether exfoliative or aspiration will be presented with explanation of its rule as a screening and diagnostic test. A brief description of the indications, utilization, sensitivity, specificity, cost effectiveness, speed and accuracy will be carried out. The role that cytopathology plays in early detection of cancer will be emphasized. The ability to provide all types of ancillary studies necessary to make specific diagnosis that will dictate treatment protocols will be demonstrated. A brief description of the general rules of cytomorphology differentiating benign from malignant will be presented. Emphasis on communication between clinicians and pathologist will be underscored. The limitations and potential problems in the form of false positive and false negative will be briefly discussed. Few representative examples will be shown. A brief description of the different techniques in performing fine needle aspirations will be presented. General recommendation for the safest methods and hints to enhance the sensitivity of different sample procurement will be given. It is hoped that this review will benefit all practicing clinicians that may face certain diagnostic challenges requiring the use of cytological material.

BSCC Code of Practice--fine needle aspiration cytology

The British Society for Clinical Cytology Code of Practice on fine needle aspiration cytology complements that on exfoliative cytopathology, which was published in the last issue (Cytopathology 2009;20:211-23). Both have been prepared with wide consultation within and outside the BSCC and have been endorsed by the Royal College of Pathologists. A separate code of practice for gynaecological cytopathology is in preparation. Fine needle aspiration (FNA) cytology is an accepted first line investigation for mass lesions, which may be targeted by palpation or a variety of imaging methods. Although FNA cytology has been shown to be a cost-effective, reliable technique its accurate interpretation depends on obtaining adequately cellular samples prepared to a high standard. Its accuracy and cost-effectiveness can be seriously compromised by inadequate samples. Although cytopathologists, radiologists, nurses or clinicians may take FNAs, they must be adequately trained, experienced and subject to regular audit. The best results are obtained when a pathologist or an experienced and trained biomedical scientist (cytotechnologist) provides immediate on-site assessment of sample adequacy whether or not the FNA requires image-guidance. This COP provides evidence-based recommendations for setting up FNA services, managing the patients, taking the samples, preparing the slides, collecting material for ancillary tests, providing rapid on-site assessment, classifying the diagnosis and providing a final report. Costs, cost-effectiveness and rare complications are taken into account as well as the time and resources required for quality control, audit and correlation of cytology with histology and outcome. Laboratories are expected to have an effective quality management system conforming to the requirements of a recognised accreditation scheme such as Clinical Pathology Accreditation (UK) Ltd.

Diagnostic accuracy of fine-needle aspiration cytology in histological grade 1 breast carcinomas: are we good enough?

BACKGROUND

Fine-needle aspiration cytology (FNAC) of both palpable and non-palpable breast carcinomas has a high accuracy and sensitivity in dedicated centres. It is generally thought that low-grade carcinomas have a distinctly lower sensitivity due to discrete cellular atypia that may be difficult to appreciate. Grade 1 carcinomas make up about 45% of screening-detected breast carcinomas and about 20% of symptomatic breast cancers. The aim of this study was to evaluate the diagnostic sensitivity of grade 1 carcinomas and identify the critical features in the cytological diagnostic work-up of these tumours.

METHODS

There were FNAC smears from 494 histologically confirmed grade 1 carcinomas diagnosed during 1996-2004. The cytological diagnoses were compared with the histology.

RESULTS

A definitive malignant diagnosis (absolute sensitivity) was given in 382 cases (77.3%). Equivocal or suspicious diagnoses were given in 75 (15.2%), benign or probably benign (false negative) in 24 (4.8%). Thirteen cases (2.6%) were unsatisfactory. Complete sensitivity was 92.7%. Invasive ductal carcinomas comprised 81.3% of all cases; absolute sensitivity for these was 80.9%. Invasive lobular and tubular carcinomas comprised 7.3% and 5.9% of cases, respectively; absolute sensitivity for these diagnosis was 50.0% and 57.1%, respectively, significantly lower than for other subtypes (P <or= 0.0001) whereas the difference for complete sensitivity was less but still significant (P = 0.017). Absolute and complete sensitivities were lower for tumours less than 1 cm size compared with more than 1 cm (P <or= 0.00001).

CONCLUSION

Preoperative FNAC diagnosis of grade 1 breast carcinoma has a high sensitivity, especially in ductal carcinomas. Invasive lobular and tubular carcinomas were less likely to receive a definite preoperative diagnosis. The main reason for not reaching a definitive malignant diagnosis was sampling error due to small tumours less than 1 cm in diameter, irrespective of tumour subtype.

Fine needle aspiration at a Regional Head and Neck Clinic: a clinically beneficial and cost-effective service

BACKGROUND

Fine needle aspiration (FNA) is an important adjuvant to the diagnosis of a palpable lesion which often permits the complete assessment of patients. The main objective of this study was to determine the clinical benefit of a dedicated FNA service at a tertiary referral Head and Neck Clinic and to assess if such a service is cost effective.

METHODS

All patients attending the Head and Neck Clinic during 2004 were prospectively assessed in this study. Patient records were analysed regarding investigative modalities including FNA, the subsequent cytology result and the requirement for further histopathological investigations. A cost analysis for all investigative procedures was performed.

RESULTS

A total of 135 patients (36 males) had FNAs performed during the study period. The median age was 51.5 years (range 17-92). Patients presented with lesions of lymph nodes (n = 46), thyroid (n = 41), salivary, parotid or submandibular glands (n = 22) and other cutaneous or cystic lesions (n = 26). Cytological grading results were; C1 = 26, C2 = 93, C3 = 8, C4 = 2 and C5 = 6. Patients with lesions C3 or above normally proceeded to further investigations. The overall cost of the FNA per episode in the out-patient clinic was pound114 per episode compared to day case open biopsy per patient of pound333 and an in-patient stay per patient was pound2371. FNA provided sufficient pathological diagnosis to avoid day case surgery in 57 patients (42.2%), and inpatient surgery in 65 patients (48.1%) resulting in a total saving of pound158 372 in 2004.

CONCLUSION

This study demonstrates the clinical benefit and cost-effectiveness of FNA services in a dedicated Head and Neck clinic.

Core needle biopsy versus fine needle aspiration biopsy: are there similar sampling and diagnostic issues?

Evidence suggests that in experienced hands fine needle aspiration biopsy (FNAB) is highly safe and effective for the evaluation of patients who have palpable breast lesions. In most cases, FNAB leads to an appropriate clinical or surgical management. FNAB can also be effectively used in evaluation of cystic lesions under ultrasound guidance. Other nonpalpable lesions can benefit from image-directed core needle biopsy (CNB). Overall, cost should influence the decision to use FNAB or CNB. FNAB may be the only affordable procedure in developing countries. Breast cancer affects significant numbers of women worldwide. Attempts should be made to take all the measures necessary to consider optimal approaches to breast health care for everyone regardless of age, race, ethnicity, or social status.

Benign follicular thyroid lesions versus follicular variant of papillary carcinoma: differentiation by architectural pattern

Differentiation between benign and malignant follicular lesions is one of the difficult diagnostic areas in thyroid fine needle aspiration (FNA). Nuclear criteria are usually used to distinguish between them. In this study the microarchitectural pattern of common benign follicular lesions, namely nodular hyperplasia (NH) and follicular adenoma (FA) were analysed in comparison with those of follicular variant of papillary carcinoma (FVPC) in order to aid in their differentiation. The FNA smears of histologically proven cases of FVPC, NH and FA were reviewed and compared. The microarchitectural features of FVPC, NH and FA were described. Three cytological features--multi-layered rosettes, branching monolayered sheets and balls of thick pinkish colloid--were exclusively observed in FVPC. Hyperplastic papillae with intact follicles and colloid were frequently seen in NH, 83% and 100%, respectively. Albeit less frequently, they were also noted in FVPC, 25% and 75% of cases, respectively. These overlapping features make the distinction between FVPC and NH sometimes difficult; however, assessing the smears for the specific features of FVPC may help in their differentiation. None of the aforementioned microscopic findings with the exception of the seldom presence of colloid were documented in FA. The crowded clusters of follicular cells were seen both in FA and FVPC; however, they were complex and branching in the latter and round to oval in the former. Finally, smears with good recovery of material are indispensable for the identification of these helpful microarchitectural patterns.

Fine needle aspiration in plastic surgery outpatients: a retrospective study

A survey suggested that fine needle aspiration cytology of masses in plastic surgery outpatient clinics was suboptimal. A cytopathologist gave training in the technique and the effectiveness of this intervention was audited. A total of 236 aspirates were taken from 147 patients in the earlier time period and 215 from 149 in the later period. The overall inadequate aspirate rate remained constant at 43%. The most common reasons for poor aspirates were excess blood, unrepresentative adipose tissue and insufficient cellular material. When the specimen was adequate after training, the sensitivity and specificity of the investigation were 96% and 100%, respectively. We present methods for sample optimization. Alternative strategies may be to limit aspiration to one clinician or to refer the patient to a cytopathologist experienced in the technique.

The role of FNA in the initial management of thyroid lesions: 7-year experience in a district general hospital

Fine needle aspiration (FNA) cytology plays a major role in the diagnosis of the thyroid lesions in university hospitals and tertiary referral institutions. Our aim was to find out if this was possible in small district hospitals with limited resources. Over a 7-year period, from October 1994 to April 2002, 303 patients with thyroid swellings underwent FNA with an overall adequacy rate of 97.7%. FNAs were performed specifically by the pathologists, so that our inadequacy rate, 2.3% was far lower than 11-29% reported elsewhere. The FNA findings were compared with subsequent histology results in 67 cases. The diagnosis of benign and neoplastic lesions was predicted accurately by FNA in 93% and 94.7% of cases, respectively. The latter reached 100% if results of FNA in follicular neoplasms were excluded. Sensitivity and specificity were 85.6% and 97.6%, respectively, which is comparable with results from tertiary institutions. The commonest thyroid lesions in our hospital were nodular goitre (52.4%), followed by thyroiditis (17.6%) and neoplasia (13.9%). We conclude that, with the availability of appropriate personnel, FNA is feasible as the major modality in district general hospitals. FNA in follicular lesions remains challenging but could be overcome in part by recognizing the criteria to differentiate follicular variant of papillary carcinoma and other follicular proliferations. Aspiration, smearing, staining and interpretation should be left to pathologists or other well-trained personnel to ensure good quality and consistency.

Head and neck lymphadenopathy: evaluation with US-guided cutting-needle biopsy

PURPOSE

To evaluate ultrasonography (US)-guided core biopsy in the assessment of 247 patients with cervicofacial lymphadenopathy.

MATERIALS AND METHODS

Two hundred sixty US-guided core biopsies were performed in 247 patients with cervicofacial lymphadenopathy. The age of the patients ranged from 1 to 91 years (mean, 50 years). Seventy-four (30%) had a history of malignancy. Biopsies were performed as outpatient procedures with direct US guidance and non-advancing 16-18-gauge core needles. Hospital records were reviewed 6 months to 5 years after biopsy. Final diagnoses were rendered based on results of histologic examination of excised specimens, clinical course, or results of other laboratory studies.

RESULTS

Two hundred thirty-eight (92%) core biopsies yielded adequate material. In 28 (11%) patients, the histologic diagnosis was considered highly probable. In the 210 patients in whom adequate material was obtained and an unequivocal histologic diagnosis was given, the sensitivity, specificity, and accuracy of US-guided core needle biopsy in differentiating benign from malignant lymphadenopathy were 98.1%, 100%, and 98.7%, respectively. Seventy biopsies were performed in 66 patients with lymphoma. Sensitivity, specificity, and accuracy in differentiating lymphoma from reactive lymphadenopathy were 98.5%, 100%, and 98.7%, respectively. In 53 patients (80%) with lymphoma as a final diagnosis, histologic subclassification was sufficient to guide treatment without the need for surgical biopsy. There were no major complications and only three minor post-biopsy hematomas.

CONCLUSION

US-guided core biopsy in patients with head and neck lymphadenopathy is a safe outpatient procedure that has a high diagnostic yield and accuracy and frequently obviates surgery.

Fine needle aspiration cytology in the work-up of mammographic and ultrasonographic findings in breast cancer screening: an attempt at differentiating in situ and invasive carcinoma

This study evaluated the results of fine needle aspiration cytology (FNAC) from the first four years of organized mammography screening for breast cancer in Oslo, particularly our policy in differentiating in situ and invasive carcinoma. Lesions were aspirated directly, ultrasound guided, by stereotaxic device or biopsy localization plate. All lesions were aspirated by cytopathologists working with the radiologists at the breast diagnostic centre. Smears were evaluated immediately for assessment of adequacy and a preliminary diagnosis was given to the surgeon. When FNAC revealed malignancy, diagnostic terms were as follows: (1) invasive carcinoma; (2) ductal carcinoma in situ of comedo type (high nuclear grade), cannot evaluate infiltration; (3) ductal carcinoma in situ of low nuclear grade and (4) papillary tumour, cannot evaluate infiltration. There were 953 cases, 70% of which were nonpalpable. Insufficient material was obtained in 5.8%. Absolute and complete sensitivity were 81% and 91%, respectively. Specificity was 85%. There were 448 histologically proven carcinomas. 383 of these were invasive. 362 carcinomas (in situ and invasive) (80.8%) were diagnosed directly on FNAC. Distinction between invasive and in situ carcinoma was possible in 294 of 320 directly diagnosed invasive carcinomas (91.8%). PPV of a diagnosis of invasive carcinoma was 97%. Our data showed that definitive cytological diagnosis of invasive carcinoma was possible in more than 90% of fully diagnostic smears and allowed definitive primary surgery in these women.

Quality assurance in a multidisciplinary symptomatic breast assessment clinic

BACKGROUND

Although quality assurance guidelines for surgeons have been issued and adopted for use in population-based breast screening programs in Australia, similar guidelines are unavailable for women referred with symptomatic breast problems.

METHODS

Six hundred and ninety-six women who attended the Royal Adelaide Hospital Women's Health Centre between February and November 1998 for investigation and management of a new breast-related complaint were prospectively evaluated. Investigation strategies and outcomes of the initial consultation were determined and the results compared with the performance quality standards for symptomatic breast disease according to the British Association of Surgical Oncology (BASO) Breast Surgeons' Group.

RESULTS

A breast lump was the presenting symptom in 45%, while breast pain was present in 26%. Ninety per cent of women referred with breast symptoms were given a definitive benign or malignant diagnosis at the initial clinic visit. Although the median time delay between the date of general practitioner referral and breast clinic appointments for all patients was < or =7 days, the time delay for 'urgent' cases was not met according to BASO performance indicators. All other Royal Adelaide Hospital Breast Clinic audit data were within the range suggested by BASO performance indicators for new consultations in a symptomatic breast assessment clinic.

CONCLUSIONS

A multidisciplinary breast clinic in a public hospital setting is able to provide clinical services to symptomatic women, with the majority of patients obtaining a confident diagnosis at the first presentation. Performance indicators for symptomatic breast disease are useful in identifying inadequacies at the clerical or clinical level which, following the implementation of subsequent changes, may lead to improvement in patient outcomes.

Improved fine needle aspiration (FNA) cytology results with a near patient diagnosis service for breast lesions

This study is a review of the quality of FNA cytology results for breast lesions approximately 18 months before and 10 months after a change from a rapid diagnosis FNA service with consultant pathologist aspirators to a conventional FNA service with clinician aspirators of varied experience. The setting was symptomatic breast clinic in a large hospital in rural New Zealand acting as a tertiary referral centre for a population of 550,000. The results were collected retrospectively and prospectively. The quality of results for pathologist aspirators (total 810) and clinician aspirators (total 403) was compared using the definitions of the NHS Breast Screening Program Guidelines for Cytology Procedures and Reporting in Breast Cancer Screening. There were statistically significant differences in specificity (biopsy cases only) with 73% for pathologists and 49% for clinicians, specificity (full) with 74% and 56%, inadequate rate with 23% and 37%, and complete sensitivity with 76% and 67%. The use of pathologist aspirators allowed the specimens to be reported in a few minutes. Specimens taken by clinicians took at least 30 min to report. The financial aspects of the two approaches are discussed. When compared with clinician aspirators, pathologist aspirators obtained better quality results and these were reported more quickly.

Fine needle aspiration (FNA) in the management of palpable masses in Ibadan: impact on the cost of care

Fine needle aspiration cytology is a relatively new technique in the management of palpable lesions in Ibadan. In the University College Hospital (UCH) Ibadan, as in most centres in Nigeria, inadequate facilities, a heavy patient load, financial constraints and an unreliable supply of basic necessities like water, often delay definitive diagnosis and management. In order to alleviate the patient's problems and provide prompt and accurate diagnosis, an FNA Cytology Clinic was set up in the Pathology Department, UCH, Ibadan, managed by the pathology team. This report represents the results of our experience. The cost effectiveness and impact on cost of care are highlighted. FNA costs N250.00 (pounds sterling 2.00), whilst cost of biopsy can vary from N5000.00 to N10000.00 (pounds sterling 35.00 to pounds sterling 70.00). A total of 752 satisfactory smears was reviewed during the 3-year period 1995-97 from various sites including breast (n = 295), lymph node (n = 183) and thyroid (n = 143). Diagnostic accuracy varied with different sites, the accuracy rate for breast, lymph node and thyroid malignancy being approximately 100%, 80% and 93%, respectively.

Does a joint ultrasound guided cytology clinic optimize the cytological evaluation of head and neck masses?

AIM

To compare the results of fine-needle aspiration (FNA) of head and neck masses performed in an ultrasound-guided cytology clinic (USGCC) staffed by a radiologist and pathologist to those obtained with specimens sent from other sources.

METHODS

Comparison of broad-category FNA diagnoses (malignant, uncertain, benign or inadequate) with the patient's ultimate clinical or pathological outcome. Because FNA outcomes are semi-quantitative, accuracy of the procedure (the proportion of all tests resulting in a true- positive or negative fine-needle aspirate) is a better measure than sensitivity or specificity. Specimens (n = 292) from the first 2 years of the USGCC are compared with 600 specimens received from other sources over the previous 4 years.

RESULTS

Accuracy was 23.4% better for specimens from the USGCC compared with those obtained by clinician guided aspiration (83.9%, 95% CI 79.7-88.1%, vs 60.5%, 95% CI 56.6-64.4%). There was an 84% reduction in inadequate specimens (from 21.5% to 3.4%). The proportion resulting in an uncertain result did not alter; 12.0% for USGCC and 11.9% for clinician-derived specimens. Improvement in accurate identification of salivary gland, lymph node, soft tissue and thyroid pathology was 27.0%, 21.2%, 18.3% and 15.8% respectively.

CONCLUSIONS

The common practice of FNA performed by clinicians produces sub-optimal results in head and neck masses. A combined approach of ultrasound-guided fine-needle aspiration of head and neck masses, with immediate assessment of the material by a pathologist, is more accurate than with specimens obtained in other ways. If the results of FNA are to be incorporated into clinical decision making, the samples are best obtained using the USGCC model.

Malignant cutaneous and subcutaneous abdominal wall lesions: a fine-needle aspiration study

Cutaneous and subcutaneous masses of the abdominal wall are uncommon. However, a variety of benign and neoplastic entities can be encountered in this region. We report a series of 22 fine-needle aspirations (FNA) of malignant cutaneous and subcutaneous lesions involving the abdominal wall. All of these lesions were metastatic neoplasms. There were 14 females and eight males, with an age range of 35-83 years (mean 65 years). Twenty-one had a previous history of malignancy. The mean interval between the primary diagnosis and FNA was 26 months (range 1.5-128 months). The sites of origin in order of decreasing frequency were colon (n = 4), ovary (n = 4), breast (n = 3), endometrium (n = 2), melanoma (n = 2), and one case each of cervix, urinary bladder, kidney, pancreas, gallbladder, and lymphoma. One case was a squamous-cell carcinoma of unknown origin. Fourteen of the 22 patients were dead at the end of this study, with a mean survival of 8.4 months (range 0.5-44 months) following FNA. One patient was alive with disease at 13 months, and seven patients were lost to follow-up. Based on this data and on review of the literature we conclude that the majority of malignant cutaneous and subcutaneous lesions of the abdominal wall subject to FNA biopsy are metastatic tumors which originate from intra-abdominal, pelvic, and retroperitoneal organs and that FNA is a highly useful technique in the assessment of these lesions of the abdominal wall.

Improved FNA cytology results with a near patient diagnosis service for non-breast lesions

AIM

To review fine needle aspiration (FNA) cytology from sites other than the breast a year before and a year after the introduction of a near patient FNA diagnosis (NPFD) service in which the FNA were performed by a pathologist and reported within a few minutes.

METHODS

The setting was a large hospital in rural New Zealand. The year before the introduction of the NPFD service was examined retrospectively, and the year after prospectively. The pattern of use and the quality of the results before and after starting the NPFD service were compared.

RESULTS

Time taken to report the specimens decreased from a few days to a few minutes. There were statistically significant changes in the following: an increase from 237 to 304 in the number of non-breast FNA performed, and in particular an increase from 65 to 113 in the number for general surgery; an increase in the use of immunolabelled flow cytometry from 0 to 19 and cell blocks from 3 to 41; an increase in specificity from 53% to 80%; a decrease in the overall inadequacy rate from 29% to 9%; and a decrease in the inadequacy rate for cancers from 9% to 2%. The cost of the non-breast FNA service increased by about 9200 Pounds a year.

CONCLUSIONS

Starting an NPFD service for sites other than the breast greatly reduced the reporting time and produced statistically significant increases in the use of FNA cytology and in the quality of the results.

Guidelines of the Papanicolaou Society of Cytopathology for fine-needle aspiration procedure and reporting. The Papanicolaou Society of Cytopathology Task Force on Standards of Practice

This guideline document was developed by the Standards of Practice Task Force of the Papanicolaou Society of Cytopathology, based on extensive literature reviews and the personal practical experience of task force members. The draft guidelines were then subjected to expert review. The task force made revisions to the drafts based on the responses received from the consultant members, who are recognized experts in fine-needle aspiration biopsy.

Comparison of the costs of fine-needle aspiration and open surgical biopsy as methods for obtaining a pathologic diagnosis

BACKGROUND

A pathologic diagnosis is usually required to determine definitive management for a palpable lesion. In this era of cost control, fine-needle aspiration (FNA) provides a low-cost alternative to open excisional biopsy. Using a broad range of cases collected over 20 years, the authors of this study sought to quantify the savings resulting from the use of FNA on superficial palpable lesions to obtain a pathologic diagnosis.

METHODS

12,452 cases collected by the cytopathology service at the Medical College of Virginia during the period 1972-1991 were used to produce a profile of case type, diagnosis, and indication for surgery. Charge-based cost estimations or Relative Value Units were calculated using the 1995 Physicians' Fee Reference or published Medicare participant fees. The charges for the FNA procedure and open surgical biopsy were compared, and all other biopsy-related costs were omitted.

RESULTS

FNA provided a sufficient pathologic diagnosis to obviate open surgical biopsy in 63-85% of the cases. Estimation of cost savings on the basis of the distribution of cases and indications for surgery suggested a savings of $250,000 to $750,000 per 1000 FNA performed, or approximately 5500 Relative Value Units.

CONCLUSIONS

This study quantifies the substantial savings that result from obtaining a pathologic diagnosis by the FNA procedure rather than open surgical biopsy.

Comparison of two methods of storing breast fine needle aspirates (FNAs) using oestrogen receptor immunocytochemical assay as a method of evaluating the storage methods

Two methods of storing fine needle aspirates were compared in 14 patients with breast cancer. The methods of storage were: (1) as a Cytospin slide prepared immediately from the aspirated material and stored at -80 degrees C; (2) as a suspension of cells in tissue culture medium, stored at -80 degrees C. The effect of storage on the cells was assessed by means of an oestrogen receptor immunocytochemical assay (ER-ICA). An ER positivity of 100% was obtained by ER-ICA staining of cells after storage method 1, whilst all of the specimens stored by method 2 were ER-negative. The data demonstrate that cells stored in tissue culture medium at -80 degrees C are not suitable for ER measurement. The storage method of choice for specimens intended for ERICA is as a Cytospin slide. The ER status of cells deposited on Cytospin slides prepared immediately and stored at -80 degrees C for 2 years could be demonstrated despite the delay in processing the specimen.