Detection of tumor cells in bone marrow of patients with prostatic carcinoma by immunocytochemical techniques

Detection and isolation of disseminated tumor cells in bone marrow of patients with clinically localized prostate cancer

BACKGROUND

Disseminated tumor cells (DTCs) have been reported in the bone marrow (BM) of patients with localized prostate cancer (PCa). However, the existence of these cells continues to be questioned, and few methods exist for viable DTC isolation. Therefore, we sought to develop novel approaches to identify and, if detected, analyze localized PCa patient DTCs.

METHODS

We used fluorescence-activated cell sorting (FACS) to isolate a putative DTC population, which was negative for CD45, CD235a, alkaline phosphatase, and CD34, and strongly expressed EPCAM. We examined tumor cell content by bulk cell RNA sequencing (RNA-Seq) and whole-exome sequencing after whole genome amplification. We also enriched for BM DTCs with α-EPCAM immunomagnetic beads and performed quantitative reverse trancriptase polymerase chain reaction (qRT-PCR) for PCa markers.

RESULTS

At a threshold of 4 cells per million BM cells, the putative DTC population was present in 10 of 58 patients (17%) with localized PCa, 4 of 8 patients with metastatic PCa of varying disease control, and 1 of 8 patients with no known cancer, and was positively correlated with patients' plasma PSA values. RNA-Seq analysis of the putative DTC population collected from samples above (3 patients) and below (5 patients) the threshold of 4 putative DTCs per million showed increased expression of PCa marker genes in 4 of 8 patients with localized PCa, but not the one normal donor who had the putative DTC population present. Whole-exome sequencing also showed the presence of single nucleotide polymorphisms and structural variants in the gene characteristics of PCa in 2 of 3 localized PCa patients. To examine the likely contaminating cell types, we used a myeloid colony formation assay, differential counts of cell smears, and analysis of the RNA-Seq data using the CIBERSORT algorithm, which most strongly suggested the presence of B-cell lineages as a contaminant. Finally, we used EPCAM enrichment and qRT-PCR for PCa markers to estimate DTC prevalence and found evidence of DTCs in 21 of 44 samples (47%).

CONCLUSION

These data support the presence of DTCs in the BM of a subset of patients with localized PCa and describe a novel FACS method for isolation and analysis of viable DTCs.

Minimal Residual Disease in Prostate Cancer

Detection of minimal residual disease (MRD) in prostate cancer over several decades has greatly informed our understanding of dissemination and recurrence, but has not yet been routinely used in clinical care. Investigators have detected MRD by identification of prostate cancer cells in the bone marrow; termed disseminated tumor cells (DTCs) and blood; termed circulating tumor cells (CTCs). Various techniques including PSA-RT PCR, PSA immunocytochemistry, cytokeratin immunocytochemistry, and immune-magnetic depletion of hematopoietic cells followed by EPCAM based positive selection, have been used. Importantly, detection of DTCs correlates with recurrence. Research into prostate cancer CTCs has intensified recently, but their use in MRD evaluation has been more limited. Investigators are using semi-automated platforms to detect and begin to study prostate cancer CTCs in patients with no evidence of disease. PSA immunocytochemistry also detects CTCs and correlates with recurrence. Emerging technologies have the potential to greatly aid research in this exciting field.

Prognostic Significance of Disseminated Tumor Cells in the Bone Marrow of Prostate Cancer Patients Treated With Neoadjuvant Hormone Treatment

Purpose

To explore whether the presence of occult disseminated tumor cells (DTCs) in the bone marrow before neoadjuvant hormone therapy influences the prognosis of patients with organ confined prostate cancer treated by radical prostatectomy.

Patients and Methods

Pretreatment bone marrow aspirates from 193 cT (1-4) pN0M0 prostate cancer patients submitted to neoadjuvant hormone therapy (mean, 8 months) followed by radical prostatectomy were immunohistochemically evaluated by anticytokeratin antibody A45-B/B3 previously validated for the detection of DTCs. Bone marrow status was compared with established clinical and histopathologic risk parameters. Patients’ outcome was evaluated using prostate-specific antigen (PSA) blood serum measurements as surrogate marker for recurrence over a median follow-up of 44 months.

Results

DTCs were detected in 44.6% of patients. Bone marrow status neither correlated with tumor grade and stage, nor with the pretreatment PSA risk category (all P values > .05). In the univariate Kaplan-Meier analysis, the presence of DTCs was a significant prognostic factor with respect to poor PSA progression-free survival (log-rank test P = .0035). Using a multivariable piecewise Cox regression model, the presence of DTCs was an independent predictor of PSA relapse (relative risk 1.82; P = .014).

Conclusion

The presence of DTCs in the bone marrow of patients with prostate cancer before neoadjuvant hormone therapy and subsequent surgery represents an independent prognostic parameter, suggesting that DTCs may contribute to the failure of current neoadjuvant hormone therapy regimens.

The comparative values of bone marrow aspirate and trephine for obtaining bone scan-targeted metastases from hormone-refractory prostate cancer

Samples of metastatic prostate cancer to bone are difficult to obtain. The aim of this study was to compare the results of bone marrow aspirate and trephine biopsy for obtaining metastatic hormone-refractory prostate cancer (HRPC) samples using previous diagnostic planar 99(m)Tc-HDP bone scans to guide the procedure. All samples taken were for the purposes of research and molecular studies on HRPC. Twenty patients with HRPC had bone marrow aspirate and trephines taken from lesions in the posterior superior iliac spine or sacro-iliac region when shown on diagnostic 99(m)Tc-HDP bone scans. Three patients also underwent plain X-ray, 18F-positron emission tomography bone scan, pelvic MRI scan and 99(m)Tc nanocolloid bone marrow scans. These images were used to assess if the extra imaging information provided, such as three-dimensional localisation of the bone metastases, was of value for target bone metastases. Cancer cells were obtained in 15/20 (75%) cases in which a trephine biopsy was attempted and 0/20 of cases in which a bone marrow aspiration was attempted. The additional information provided by the range of other imaging investigations was of little benefit in obtaining tumour samples, but did suggest why negative biopsies were obtained in some cases after targeting with planar bone scans. We recommend the use of bone marrow trephine biopsy alone, guided by previous diagnostic 99(m)Tc planar bone scan as a practical method to obtain prostate cancer cells from bone metastases.

Bone marrow micrometastasis in breast cancer

BACKGROUND

Several studies have demonstrated that bone marrow micrometastasis in patients with breast cancer is an independent prognostic factor for systemic recurrence and poorer survival.

METHODS

This review describes the detection and clinical significance of micrometastatic cells in bone marrow, and examines the correlation between such micrometastasis and established clinicopathological prognostic factors. The relevant English language literature on bone marrow micrometastasis in breast cancer was searched via Medline (1975-2002), cross-referencing with key articles on the subject.

RESULTS AND CONCLUSION

The balance of evidence favours the hypothesis that bone marrow micrometastasis impacts on disease-free and overall survival. Further prospective studies are required to examine this in greater detail, with particular reference to early node-negative breast cancer and the value of adjuvant systemic therapy in patients with bone marrow micrometastasis.

Bone marrow biopsy: interpretive guidelines for the surgical pathologist

Ideally, the bone marrow core biopsy should be reviewed with knowledge of the clinical history, complete blood count, and findings in the peripheral blood and bone marrow aspirate smears. However, for a variety of reasons, the pathologist may receive the core biopsy and aspirate clot section without all of this information. Although this approach is not optimal, a great deal of valuable information can be generated from these specimens. Over the past 20 years, there has been considerable progress in the fields of flow cytometric analysis, immunohistochemistry, and molecular diagnostic studies that can be performed on smears or extracted DNA from paraffin embedded tissue. These modalities have augmented and refined diagnostic criteria formerly ascertained by light microscopy, cytochemistry, and cytogenetics. This is particularly true of some myeloid and lymphoreticular neoplasms where a collaborative and multidisciplinary approach to the diagnosis has become necessary. Despite this growing complexity and dependence on newer methodologies, the traditional role of histopathology in evaluating the bone marrow biopsy remains as important as it has been in the past. In this review, we focus on contemporary practices and expectations for interpreting bone marrow biopsies and clot sections.

Occult metastasis

The most important factor affecting the outcome of patients with invasive cancers is whether the tumor has spread, either regionally (to regional lymph nodes) or systemically. However, a proportion of patients with no evidence of systemic dissemination will develop recurrent disease after primary 'curative' therapy. Clearly, these patients had occult systemic spread of disease that was undetectable by methods routinely employed (careful pathological, clinical, biochemical and radiological evaluation). In addition, the success of adjuvant therapy is assumed to stem from its ability to eradicate occult metastases before they become clinically evident [1]. Therefore, methods for the detection of occult metastases in patients with the earliest stage of cancer, i.e., prior to detection of metastases by any other clinical or pathological analysis, have received a great deal of attention.

Stromal cells regulate survival of B-lineage leukemic cells during chemotherapy

Approximately 20% of B-lineage acute lymphoblastic leukemias are not cured by traditional chemotherapy. The possibility was examined that residual leukemic cells that potentially contribute to relapse are harbored in association with fibroblastic stromal cells in the bone marrow. Modulation of cytarabine (Ara-C) and etoposide (VP-16) efficacy by bone marrow stromal cells in vitro was investigated. Stromal cell coculture was shown to sustain the proliferation of B-lineage leukemic cells and to reduce leukemic cell apoptosis when exposed to Ara-C or VP-16. Direct contact with stromal cells was essential for the protection of leukemic cells during chemotherapy, whereas soluble factors had negligible effect. Specifically, signaling mediated through interaction with the stromal cell adhesion molecule VCAM-1 was required to maintain the maximum viability of leukemic cells during Ara-C and VP-16 exposure. In contrast, the interaction of leukemic cells with fibronectin did not confer significant resistance to either chemotherapeutic agent. These observations suggest a role for the bone marrow microenvironment in modulating the response of B-lineage leukemic cells to Ara-C or VP-16, and they indicate specific molecular interactions that may be important in determining the sensitivity of leukemic cells to treatment.

Stromal cells regulate survival of B-lineage leukemic cells during chemotherapy

Approximately 20% of B-lineage acute lymphoblastic leukemias are not cured by traditional chemotherapy. The possibility was examined that residual leukemic cells that potentially contribute to relapse are harbored in association with fibroblastic stromal cells in the bone marrow. Modulation of cytarabine (Ara-C) and etoposide (VP-16) efficacy by bone marrow stromal cells in vitro was investigated. Stromal cell coculture was shown to sustain the proliferation of B-lineage leukemic cells and to reduce leukemic cell apoptosis when exposed to Ara-C or VP-16. Direct contact with stromal cells was essential for the protection of leukemic cells during chemotherapy, whereas soluble factors had negligible effect. Specifically, signaling mediated through interaction with the stromal cell adhesion molecule VCAM-1 was required to maintain the maximum viability of leukemic cells during Ara-C and VP-16 exposure. In contrast, the interaction of leukemic cells with fibronectin did not confer significant resistance to either chemotherapeutic agent. These observations suggest a role for the bone marrow microenvironment in modulating the response of B-lineage leukemic cells to Ara-C or VP-16, and they indicate specific molecular interactions that may be important in determining the sensitivity of leukemic cells to treatment.

RT-PCR-based detection of occult disseminated tumor cells in peripheral blood and bone marrow of patients with solid tumors. An overview

Despite recent progress in early detection and local curative therapy, patients with primary epithelial cancer quite frequently relapse with incurable metastasis. Early disseminated tumor cells that may be seminal for distant failure and are undetectable by current diagnostic methods have been identified by immunocytochemical techniques in bone marrow of cancer patients using monoclonal antibodies against cytokeratins. Recently, promising new molecular approaches, namely, reverse transcriptase--polymerase chain reaction (RT-PCR) assays, have been suggested as a potential technique for the detection of minimal residual tumor burden by targeting mRNA transcribed from epithelial genes in bone marrow, peripheral blood, or lymph nodes. Several studies using RT-PCR thus far indicate a highly sensitive and specific staging tool, although the prognostic value is still controversial. However, limitations may arise from ectopic expression of marker mRNA in hematopoietic cells and deficient expression in circulating tumor cells. The present review focuses on the relevant literature and demonstrates the range of current applications of RT-PCR-based assays for detecting disseminated tumor cells in peripheral blood and bone marrow of patients with solid tumors. We will both summarize technical evaluations of published molecular approaches and discuss the widely disparate results on PCR findings in clinical studies.

Micrometastatic bone marrow involvement: detection and prognostic significance

The present review focuses on the methodology and clinical significance of new diagnostic approaches to identify individual cancer cells present in bone marrow, both as a frequent site of metastasis formation and an indicator organ for hematogenous tumor cell dissemination. The steadily increasing number of studies on this issue is characterized by considerable methodological variations of important variables, such as the size of the study population, and the reliability of monoclonal antibodies used for tumor cell detection. Emerging data indicate that this disturbing heterogeneity might be overcome by the use of reliable and specific anti-cytokeratin antibodies (for example, A45-B/B3) as, for the time, standard markers for the detection of micrometastatic tumor cells in bone marrow. Prospective clinical studies have shown that immunoassays based on anti-CK antibodies identify patients' subgroups with a poor clinical prognosis with regard to early metastasis manifestation and reduced overall survival in various epithelial tumor entities, including breast, colon, rectum, stomach, esophagus, prostate, renal, bladder, and non-small cell lung cancer. The immunocytochemical assays may be therefore used to improve tumor staging with potential consequences for adjuvant therapy, because disseminated cells appeared to be dormant, non-cycling (for example Ki-67 antigen-negative) cells, suggesting a resistance to cell-cycle dependent therapy, such as chemotherapy. Therefore, cell-cycle independent antibody-based immunotherapy might be an interesting option to complement chemotherapy. Another promising clinical application is monitoring the response of micrometastatic cells to adjuvant therapies, which, at present, can only be assessed retrospectively after an extended period of clinical follow-up. The outlined current strategies for detection and characterization of cancer micrometastasis might help to design and control new therapeutic strategies for secondary prevention of metastatic relapse in patients with operable primary carcinomas.

Outcome of primary-breast-cancer patients with micrometastases: a long-term follow-up study

BACKGROUND

Bone-marrow micrometastases have been found in patients with primary breast cancer. We report long-term follow-up of women with primary breast cancer, diagnosed between 1981 and 1986, who had multiple aspirates taken at the time of initial surgery.

METHODS

350 women with primary breast cancer were examined immunocytochemically with antibody to epithelial membrane antigen. We investigated associations with various prognostic factors as well as the effect of micrometastases on relapse-free survival and overall survival.

FINDINGS

At median follow-up of 12.5 years, 151 patients had metastatic disease and 136 patients had died from breast cancer. 10-year relapse-free and overall survival were 43.9% (95% CI 33.4-54.7) and 44.9% (34.2-55.9) in patients with micrometastases, and 62.7% (56.5-68.6) and 65.7% (59.4-71.5) in patients without micrometastases at presentation (p<0.001). For relapse-free survival and overall survival, allowing for tumour size, lymph-node status, and vascular invasion, the effect of micrometastases decreased and was no longer significant, with a hazard ratio of 1.09 (0.74-1.61) for relapse-free survival and 1.21 (0.84-1.75) for overall survival.

INTERPRETATION

The presence of bone-marrow micrometastases in patients with primary breast cancer is associated with a shorter relapse-free survival and overall survival, but is not an independent prognostic factor. This immunocytochemical technique may be of value in patients for whom pathological tumour size and lymph-node status are unavailable (ie, patients receiving primary medical treatment).

Prognostic significance of micrometastatic bone marrow involvement

The present review focuses on the methodology and clinical significance of new diagnostic approaches to identify micrometastatic breast cancer cells present in bone marrow (BM), as a frequent site of overt metastases. Using monoclonal antibodies (mAbs) to epithelial cytokeratins (CK) or tumor-associated cell membrane glycoproteins, individual carcinoma cells can be detected on cytologic BM preparations at frequencies of 10(-5) to 10(-6). Prospective clinical studies have shown that the presence of these immunostained cells is prognostically relevant with regard to relapse-free and overall survival. The current interest in autologous bone marrow transplantation in patients with solid tumors further underlines the need for screening methods that allow the detection of minute numbers of residual tumor cells in the transplant. Although the development of new molecular detection methods based on the amplification of a marker mRNA species by the polymerase chain reaction technique is a very exciting area of research, the clinical significance of this approach needs to be demonstrated in prospective studies. The immunocytochemical assays may be, therefore, used to improve tumor staging with potential consequences for adjuvant therapy. Another promising clinical application is monitoring the response of micrometastatic cells to adjuvant therapies, which, at present, can only be assessed retrospectively after an extended period of clinical follow-up. The extremely low frequency of BM tumor cells greatly hampers approaches to obtain more specific information on their biological properties. The available data indicate that these cells represent a selected population of cancer cells which, however, still express a considerable degree of heterogeneity with regard to the expression of MHC class I antigens, adhesion molecules (EpCAM), growth factor receptors (EGF receptor, erb-B2, transferrin receptor), or proliferation-associated markers (Ki-67, p120). Regardless of the detection technique applied, there is an urgent demand for large multicentre trials, in which standardized methods are related to specified clinical outcomes.

Detection of occult metastases in lung carcinomas: progress and implications for lung cancer staging

The ability to detect occult regional and systemic metastases in patients with operable lung carcinoma could have a significant impact on the management of the disease. Here, we review the literature, including studies from our own laboratory, regarding the clinical significance of the presence of occult metastases in patients with lung cancer. The accumulated evidence strongly suggests that the detection of occult regional and systemic metastases is an important predictor of disease progression. The use of this method should be considered in the future design of lung cancer clinical trials, at the very least. The detection of occult metastases should have an impact on lung cancer management; to reflect this, we propose a change in the TNM staging system to indicate the presence or absence of occult regional (lymph node) and systemic (bone marrow) metastases. The proposed change is TNnMm, where n and m are occult nodal and bone marrow metastases status.

In vitro detection of occult bone marrow metastases in patients with colorectal cancer hepatic metastases

PURPOSE

The purpose of this study was to assess the immunocytochemical status of bone marrow aspirates from patients with clinically isolated hepatic metastases to test the hypothesis that such findings would allow improved patient selection for liver-directed treatment.

METHODS

All patients had biopsy-proven or presumed colorectal cancer metastatic to the liver and were scheduled for an operative procedure for hepatic resection or for hepatic artery catheter and chemotherapy pump implant. Immunocytochemical analysis of bone marrow aspirate smears was performed with a panel of monoclonal antibodies directed toward cytokeratins, Lewis Y antigen and A-33 colorectal epitopes.

RESULTS

Data from 80 patients indicated that bone marrow reactivity was present in 9.5 percent of those with resectable hepatic metastases and in 34 percent of those not resected (P = 0.03). No single monoclonal antibody or combination produced better discrimination.

CONCLUSIONS

Presence or absence of presumed occult colorectal cancer cells in the bone marrow of patients with isolated hepatic metastases is biologically interesting, but not useful in selecting or altering patient management.

Prostate-specific antigen-producing cells in the bone marrow of a patient with early-stage prostate cancer

This report describes a clinical case that supports the hypothesis that occult bone marrow disease may exist even in early-stage and low prostate-specific antigen (less than 10 ng/mL) prostate cancer. The concept of adding androgen suppression to definitive local therapy in these patients is discussed.

Detection of micrometastatic prostate cancer cells in the bone marrow of patients with prostate cancer

Thirty-five patients with prostate cancer were examined for micrometastases to the bone marrow using reverse transcription-polymerase chain reaction (RT-PCR) with primers specific for the prostate-specific antigen (PSA) gene. Of nine patients with bone metastases detectable by bone scan imaging, five patients had PSA mRNA expression in the bone marrow detectable by RT-PCR. Of 26 patients with negative bone scan findings, seven patients had PSA mRNA expression detectable in the bone marrow. RT-PCR could detect micrometastatic prostate cancer cells in the bone marrow that were not detectable by bone scan imaging. Of 16 patients with a serum PSA concentration of 25 ng ml(-1) or greater, only nine (56.3%) had bone metastases detected by bone scans. Of the remaining seven patients, five had micrometastases to the bone marrow detected by RT-PCR. Overall, 14 of 16 patients (87.5%) with a serum PSA concentration of 25 ng ml(-1) or greater had metastatic bone diseases including bone marrow micrometastases. Of 19 patients with a serum PSA concentration of less than 25 ng ml(-1), two (10.5%) had only micrometastatic disease detected by RT-PCR. A significant correlation was observed between the incidence of bone involvement and the serum PSA concentration. This study suggests that RT-PCR will potentially develop into a relevant tool to assess bone involvement including bone marrow micrometastases and establish a precise correlation between serum PSA concentration and metastatic bone disease in patients with prostate cancer.

Detection of minimal disease in patients with solid tumors

The detection and elimination of minimal systemic disease in patients with solid tumors is one of the main current topics in clinical oncology. The present review focuses, therefore, on new diagnostic approaches to identify minimal disease in peripheral blood, bone marrow, and lymph nodes of patients with epithelial cancer as the major type of solid tumors in Western industrialized countries. These approaches may be used to improve tumor staging and monitoring of adjuvant therapies, as well as to detect tumor cell contamination in autologous stem cell grafts. Most investigators have developed either immunocytochemical assays with monoclonal antibodies to a variety of epithelial-specific cytoskeleton and membrane antigens or molecular methods based on the extensive amplification of a specific (c)DNA sequence by the polymerase-chain reaction (PCR). In immunocytochemical assays, antibodies to cytokeratins can be regarded as the most specific and sensitive probes to detect isolated epithelial tumor cells in bone marrow and blood. Molecular methods are based on the detection of either mutations in oncogenes and tumor suppressor genes (e.g., ki-ras and p53 genes) or the mRNA expression of tissue-specific and tumor-associated genes. mRNA species targeted in these assays encode cytokeratins, prostate-specific antigen, prostate-specific membrane antigen, carcinoembryonic antigen, and polymorphic-epithelial mucin. To introduce the available methods into clinical practice, standardized protocols need to be developed and validated in multi-center studies.

Immunocytochemical detection of isolated tumour cells in bone marrow of patients with untreated stage C prostatic cancer

The micrometastatic spread of tumour cells is usually missed by conventional diagnostic techniques, although this spread largely determines the prognosis of patients with primary epithelial cancers. By use of the monoclonal antibody, CK2, to epithelial cytokeratin component number 18 (CK18), individual disseminated carcinoma cells present in bone marrow of cancer patients can now be identified. In the present study, this approach has been applied to patients with virginal stage C adenocarcinoma of the prostate. Double-sided aspirates of iliac bone marrow from 24 of 44 evaluable patients (54.4%) exhibited between one and 38 CK18-positive cells per sample of 2 x 10(6) mononuclear cells. In 13 of these 24 positive patients, CK-positive cells were only detected in one of the two aspirates analysed. There was no statistically significant correlation between this finding and established risk factors, such as the volume and histological grade of the primary tumour or the concentration of prostate specific antigen and prostatic acid phosphatase in serum. The follow-up time is too short to provide meaningful data on the prognostic significance of isolated CK18-positive cells in bone marrow, which, however, has been recently demonstrated in other types of primary epithelial cancers. In conclusion, the presence of prostatic tumour cells in bone marrow might be interpreted as an indicator of the metastatic capacity of an individual primary tumour. The immunocytochemical detection of these cells may, therefore, be useful for increasing the precision of current tumour staging, and to monitor minimal residual cancer in an individual patient.

Incidence of occult lymph node metastases in pathological stage C (pT3N0) prostate cancer

PURPOSE

To determine the incidence of occult lymph node metastases in patients with stage pT3N0 prostate cancer.

MATERIALS AND METHODS

Lymph nodes from 95 patients with stage pT3N0 prostate cancer were analyzed by immunohistochemistry for extrinsic epithelial cells using epithelial-specific monoclonal antibodies. The extrinsic epithelial cells were also tested for prostate specific antigen expression.

RESULTS

Occult lymph node metastases were identified in 15 cases (16%) and were more frequent in patients with high primary Gleason grade tumors and seminal vesicle invasion (p = 0.03). In all cases the extrinsic cells were of prostate origin based on prostate specific antigen expression.

CONCLUSIONS

Occult lymph node metastases can be detected in a substantial proportion of patients with stage pT3N0 prostate cancer, are associated with known predictors of disease progression, and may be useful in identifying patients at risk for recurrence and progression.

Detection of occult micrometastases in the bone marrow of patients with prostate carcinoma

A panel of three monoclonal antibodies that recognize membrane and cytoskeletal antigens expressed by epithelial cells (T16, C26, and AE-1) was used in a sensitive immunohistochemical assay to detect tumor cells in bone marrow aspirates from 20 patients with prostate cancer. Bone marrow aspirates from 2/9 (22%) patients with localized prostate cancer (stage B, 0/5; Stage C, 2/4), and 4/11 (36%) patients with metastatic prostate cancer (Stage D1, 0/7 patients; Stage D2, 4/4 patients) had antigen-positive cells in their bone marrow. The patients with localized disease had conventional examinations for metastases, including radioisotope bone scans and examination of bone marrow cytology, which were negative. The serum prostatic specific antigen (PSA) level appeared to correlate with the presence of micrometastases. Those patients with localized disease and antigen-positive cells in the bone marrow had an average serum PSA level of 26.6 ng/ml, while the average serum PSA level in patients without antigen-positive cells was 12.3 ng/ml. In addition, the number of antigen-positive cells detected appeared to correlate with the stage of disease; patients with Stage C prostate cancer had an average of 10 antigen-positive cells per one million bone marrow elements, while patients with Stage D2 disease had an average of 25 antigen-positive cells per one million bone marrow elements. We have demonstrated that immunohistochemical staining of bone marrow aspirates can detect occult bone marrow metastases in patients with apparently localized prostate cancer. Further follow-up of these and a larger number of patients will be require to determine the potential clinical significance of this finding.

Detection and characterization of residual disease in breast cancer

Although micrometastatic tumor cell spread largely determines the prognosis of patients with operable breast cancer, it is usually missed by conventional tumor staging. Several groups (including ours) have therefore developed immunocytochemical and molecular assays that allow the specific detection and characterization of individual carcinoma cells disseminated to bone marrow, blood, and lymph nodes. These assays may improve the prognostic precision of the current classification systems and may provide a tool for the early assessment of the therapeutic effects of anticancer drugs on micrometastatic cells in individual patients. Another aspect of such methods is that they enable detection of tumor cell contamination in stem cell grafts and validation of the efficiency of purging techniques. The most extensive experience exists with immunocytochemical methods, some of which have the potential to serve as a benchmark for less validated molecular methods. Still, the specificity and sensitivity of immunocytochemical detection of single cancer cells are affected by several variables, which include the intricacies of antigen expression, the lack of distinct morphological characteristics, the size of the analyzed sample, and the staining techniques for visualization of antibody binding. This article provides a critical review of the opportunities and pitfalls related to new methods for the detection and monitoring of minimal residual disease in breast cancer.

Residual tumor (R) classification and prognosis

The tumor status following treatment is described by the residual tumor (R) classification: R0, no residual tumor; R1, microscopic residual tumor; R2, macroscopic residual tumor. Residual tumor may be found in the area of primary tumor and its regional lymph nodes and/or at distant sites. The R classification reflects the effects of treatment and influences further treatment planning. Furthermore, the R classification is a strong predictor of prognosis. An acceptable long-term prognosis can be expected only in R0 patients. Although there exist clear correlations between stage and R classification the differences in prognosis of R0 versus R1,2 cannot be explained by differences in stage alone. The prognostic significance of R classification is demonstrated by respective data for non-small cell lung carcinoma, squamous cell carcinoma of oesophagus, gastric carcinoma, ductal adenocarcinoma of the pancreas, colorectal carcinoma, lung and liver metastases.

Chemo-endocrine therapy for prostate cancer with bone metastasis. Nagasaki Prostate Cancer Research Group

We analyzed the clinical effects of initial chemoendocrine therapy on 31 prostate cancer patients with bone metastasis. These patients had been newly diagnosed between 1983 and 1991 and had received no previous therapy. As endocrine therapy, the patients received 1 mg ethynylestradiol daily with or without orchiectomy. In addition, they received three courses of chemotherapy consisting of 20 mg/m2 cisplatin given on days 1, 3, and 5 and 20 mg/m2 Adriamycin or 40 mg/m2 epirubicin given on day 5. Subsequently, for maintenance therapy, the patients received 1 mg ethynylestradiol and 150 mg 5-fluorouracil [or 300 mg tegafur plus uracil (UFT)] daily. Patients given our regimen of chemoendocrine therapy had a significantly better prognosis than did the controls treated with endocrine therapy alone (P = 0.05), although treatment was not randomized. The cause-specific survival rates at 5 years for the chemoendocrine-therapy patients and the control group were 65.4% and 37.4%, respectively. A multivariate analysis of possible prognostic factors, i.e., age, histological grade, prostatic acid phosphatase, tumor-related pain, the extent of disease (EOD) on bone scan, and the type of initial treatment, confirmed that the initial treatment (P = 0.03) and the EOD grade (P = 0.05) had a significant effect on survival. On the basis of these results, it is necessary to carry out a randomized trial to compare our chemoendocrine regimen with endocrine therapy alone in untreated patients with advanced prostate cancer.

Prophylactic treatment of skeletal metastases, tumor-induced osteolysis, and hypercalcemia in rats with the bisphosphonate Cl2MBP

BACKGROUND

The purpose of this study was to investigate the influence of a prophylactic bone protective treatment with the bisphosphonate dichloromethane/diphosphonic acid (Cl2MBP) in an experimental model of osteolysis with intraosseous implantation of the Walker carcinosarcoma 256 B.

METHODS

The biphosphonate was given as a high-dose, short-term treatment (30 mg/5 days sc) followed by a treatment-free interval (1-7 weeks) or as a low-dose, long-term prophylactic treatment (2.5 or 5.0 mg/day/3 weeks sc). Osteolysis was measured with a radiographic and histologic grading system.

RESULTS

The high-dose short-term prophylactic treatment was shown clearly to inhibit tumor osteolysis. The osteoprotective effect decreases with increasing length of the treatment-free interval. A similar positive result could be achieved following the low-dose long-term prophylactic treatment. Dosage could not be shown to influence the inhibition of tumor osteolysis in the long-term bone protective treatment. A possible direct influence of the treatment on tumor growth could be ruled out. The prophylactic treatment does not inhibit body weight increase. Animals treated prophylactically showed less weight loss than the controls after tumor implantation.

CONCLUSIONS

These results show that a prophylactic treatment with Cl2MBPs protects the skeleton effectively against tumor osteolysis.

The future of prognostic factors in outcome prediction for patients with cancer

The anatomic description of the extent of tumor spread (tumor staging) assists clinical management, facilitates communication among physicians, is an essential part of randomized controlled trials, and may help in the counseling patients and their families. However, in recent years, additional "prognostic factors" have been defined, many of which assess or reflect the biologic behavior of malignant neoplasms. Other measures of tumor biochemistry address the natural history of neoplastic development and often are included in a discussion of new prognostic factors. This review article summarizes current knowledge and thinking related to tumor prognostic factors in four areas by providing: (1) a definition and principles of anatomic spread of tumor (staging) and some suggestions for improvement, (2) a description of some examples of additional factors of prognostic significance, (3) some statistical methods to evaluate prognostic factors, and (4) an examination of the possible future of summary statements of outcome (i.e., prognostic indexes).

Monoclonal antibodies in the detection and therapy of micrometastatic epithelial cancers

The initial promise of monoclonal antibodies as major therapeutic agents in human epithelial cancer has not been realized. Inaccessibility of cells in solid tumors due to factors such as the nature of the vascular endothelia and high pressure in the tumor are primarily responsible for the failure of antibody therapy. Although new strategies employing recombinant antibodies and immunoglobulins designed to actively engage the immune system may prove beneficial, micrometastatic tumor cells (at the stage of minimal residual disease) are likely to be the only suitable targets for antibody therapy. The diagnostic approaches to identify and characterize these cells and their use for prognosis and monitoring adjuvant immunotherapy is discussed.

Selection of appropriate cellular and molecular biologic diagnostic tests in the evaluation of cancer

In this article, the use of cellular and molecular markers to diagnose and stage tumors is discussed. Their role in the evaluation of tumor prognosis and tumor susceptibility also is covered. The immunologic, cytogenetic, and molecular phenotype is discussed. Traditional markers are compared with newer methodologic approaches including evaluation of oncogenes, tumor suppressor genes, and genes that predict tumor susceptibility. These discussions are presented in relation to specific tumors. Finally, statements one might use to decide which tests to perform are presented.