Radioguided-surgery of early breast lesions

BACKGROUND

Radioguided-surgery has been recently proposed in patients with clinically occult breast lesions. This study aimed to evaluate the feasibility of correctly locating and eradicating, by a single intralesional injection of a radiotracer, any breast lesion and, in the case of malignancy, to perform simultaneous sentinel lymph node (SLN) biopsy procedure.

PATIENTS AND METHODS

Sixty-three women with early breast lesions were enrolled: 42 were invasive carcinomas, 16 in situ ductal carcinomas (DCIS) and 5 fibroadenomas.

RESULTS

Scintigraphic images clearly identified the lesions in all patients while SLN/s were evident in 88% of them. At surgery all the breast lesions were easily radiolocalized and eradicated with minimum surgical trauma and, for those patients with invasive carcinomas, the SLN technique was performed in 86% of them. No skip metastases were found.

CONCLUSION

A single intralesional administration of radiotracer is an easy and reliable procedure to simultaneously locate and remove both the non-palpable breast lesion and the SLN when primary malignancy was intraoperatively confirmed.

In vivo evaluation of bismuth-labeled monoclonal antibody comparing DTPA-derived bifunctional chelates

Among the radionuclides considered for radioimmunotherapy, alpha-emitters such as the bismuth isotopes, 212Bi and 213Bi, are of particular interest. The macrocyclic ligand, DOTA, has been shown to form stable complexes with bismuth isotopes. The kinetics of the complexation of bismuth with the DOTA chelate, however, are slow and impractical for use with 212Bi and 213Bi that have half-lives of 60.6 and 45.6 min. The study described herein compares six DTPA derived bifunctional chelates with the goal of identifying an alternative to the DOTA ligand for radiolabeling with bismuth. Radioimmunoconjugates comprised of MAb B72.3, each of the six DTPA chelates, and radiolabeled with 206Bi, which facilitated the evaluation due to its readily detectable gamma-emission. In vitro studies showed that each of the radioimmunoconjugates retained immunoreactivity that was comparable to its 125I-labeled counterpart. The 206Bi- and 125I-labeled immunoconjugates were then co-injected i.p. into normal athymic mice. Injection of Afree@ 206Bi demonstrated that the kidneys were the critical organ to evaluate for retention of bismuth in the chelate complex. Major differences were identified among the six preparations. The CHX-A and -B immunoconjugates were found to have 1) the lowest %ID/gm in the kidney; 2) a level of 206Bi in the kidney that was comparable to that of 125I-B72.3; and 3) no significant uptake of 206Bi evident in other organs such as bone, lung and spleen. The results described herein suggest that either of the cyclohexyl derivatives of DTPA may be suitable candidates for the labeling of immunoconjugates with alpha-emitting bismuth isotopes for radioimmunotherapeutic applications.

Detection of blood-borne cells in colorectal cancer patients by nested reverse transcription-polymerase chain reaction for carcinoembryonic antigen messenger RNA: longitudinal analyses and demonstration of its potential importance as an adjunct to multiple serum markers

The use of reverse transcription-PCR (RT-PCR) to analyze cells in the blood of cancer patients for the detection of mRNA expressed in tumor cells has implications for both the prognosis and the monitoring of cancer patients for the efficacy of established or experimental therapies. Carcinoembryonic antigen (CEA) is expressed on approximately 95% of colorectal, gastric, and pancreatic tumors, and on the majority of breast, non-small cell lung, and head and neck carcinomas. CEA shed in serum is useful as a marker in only approximately 50% of colorectal cancer patients and rarely is shed by some other carcinoma types. RT-PCR has been used previously to detect CEA mRNA in cells in the blood and lymph nodes of cancer patients. Under the assay conditions validated in the studies reported here, 34 of 51 (67%) patients with different stages of colorectal cancer had blood cells that were positive by RT-PCR for CEA mRNA, whereas none of 18 patients with colonic polyps were positive; 2 of 60 apparently healthy individuals (who were age and sex matched with the carcinoma patients and were part of a colon cancer screening program as controls) were marginally positive. The results of CEA PCR in the blood of the carcinoma patients and the other groups showed strong statistical correlation with the disease (P2 < 0.0001). Analyses were carried out to detect both serum CEA protein levels and CEA mRNA in blood cells of colorectal carcinoma patients by RT-PCR. For all stages of disease, 18 of 51 patients (35%) were positive for serum CEA, whereas 35 of 51 (69%) were positive by RT-PCR. More importantly, only 5 of 23 (20%) of stage B and C colorectal cancer patients were positive for serum CEA, whereas 16 of 23 (70%) were positive by RT-PCR. The use of two other serum markers (CA19.9 and CA72-4) for colorectal cancer in combination with serum CEA scored two additional patients as positive; both were positive by RT-PCR for CEA mRNA. Pilot long-term longitudinal studies conducted before and after surgery identified some patients with CEA mRNA in blood cells that were negative for all serum markers, who eventually developed clinical metastatic disease. The studies reported here are the first to correlate RT-PCR results for CEA mRNA in blood cells with one or more serum markers for patients with different stages of colorectal cancer, and are the first long-term longitudinal studies to use RT-PCR to detect CEA mRNA in blood cells of cancer patients. Larger cohorts will be required in future studies to define the impact, if any, of this technology on prognosis and/or disease monitoring.

Comparative analysis of CA 242 and CA 19-9 serum tumor markers in colorectal cancer patients. A longitudinal evaluation

OBJECTIVE

Following the encouraging results obtained on CA 242 as an adjunctive marker for colorectal cancer this study was designed to compare the clinical behavior of CA 242 to that of its related marker CA 19-9.

PATIENTS AND METHODS

Sera from 630 patients with benign (n = 201) or malignant (n = 429) colorectal diseases were evaluated. Moreover, 50 patients with colorectal cancer were longitudinally monitored during. post-surgical follow-up for either a minimum of 5 years or until time of recurrence. Serum CEA, CA 19-9 and CA 242 levels were determined before treatment and at each scheduled follow-up.

RESULTS

The distribution of CA 242 levels in colorectal cancer patients demonstrated a similar positivity rate (32.9%) compared to that of CA 19-9 (29.8%), although both sensitivities were lower than that of CEA (43.8%). Moreover, elevated CA 242 serum levels were found in metastatic disease (58.2%). A longitudinal evaluation demonstrated that serum CEA, CA 19-9 and CA 242 levels were elevated in 63.9%, 63.9% and 66.7% of recurrences. Combined evaluation of CEA, CA 19-9 and CA 242 serum levels in the overall population demonstrated a complementarity of CEA with the latter two markers. Conversely, a highly significant correlation was observed, suggesting that the two assays might recognize the same macromolecular complex.

CONCLUSION

CA 242 determination does not seem to offer a particular advantage over CA 19-9, while CEA remains the marker of choice in monitoring colorectal cancer patients.

A neuroepidemiological survey in rural Bolivia: background and methods

A door-to-door survey was carried out in rural areas of the Cordillera province, Santa Cruz Department, Bolivia. A cluster sample of 10,124 inhabitants was selected. The aim was to determine the prevalence of the most common neurological diseases (epilepsy, stroke, parkinsonism and peripheral neuropathy) in this population using a modification of the World Health Organization screening instrument. 1,130 subjects screened positive and were then investigated by neurologists. In this paper we describe the background and methods of the survey and the characteristics of the population.

CA 19-9 monosialoganglioside content of human colorectal tumor cells correlates with tumor cell-induced platelet aggregation

BACKGROUND

Gangliosides are involved in tumor cell-induced platelet aggregation (TCIPA). CA 19-9 is a monosialoganglioside detected in colon carcinoma cells. Therefore, this study was designed to evaluate whether there was any correlation between the CA 19-9 monosialoganglioside content and TCIPA.

MATERIALS AND METHODS

The CA 19-9 content was determined on gangliosidic extracts of human colorectal tumor cells (GEO, WiDr, DLD-1, MIP) in comparison with the degree of TCIPA.

RESULTS

CA 19-9 was detected in all cell lines, except MIP. The mean CA 19-9 content was 10.2, 30.2 and 82.6 U/microgram of sialic acid for GEO, DLD-1 and WiDr, respectively. CA 19-9 content directly correlated with TCIPA (p < 0.0001). Furthermore, incorporation of exogenous gangliosides in GEO cells resulted in an increase of CA 19-9 content, paralleled by a concomitant increase of TCIPA.

CONCLUSIONS

The CA 19-9 monosialoganglioside may be involved in platelet/tumor cell interactions, thus playing an important role in the haematogenous metastases of colorectal cancer.

The role of sentinel node biopsy in breast cancer management: an overview

Regional lymph nodes surgical management is an integral part of breast cancer therapy. One of the most important therapeutic problems is the risk of surgical treatment which is too wide or inadequate due to the lack of correct presurgical information on the conditions of regional lymph nodes. For melanoma the problem was solved combining surgical accuracy with the slightest surgical resection, using sentinel node biopsy. In breast cancer the removal of axillary nodes proved to be unnecessary in more than 50% of cases. The first international studies on the use of sentinel node biopsy in breast carcinoma for the identification of patients who do not need axillary clearance suggest the high accuracy of the technique. Some practical problems still exist, however, and the optimisation of the method is not yet complete. The use of sentinel node biopsy in breast cancer treatment might be able to provide distinctive clinical information, which can improve our knowledge about the disease?'s biological behaviour and about its treatment.

Prevalence of epilepsy in rural Bolivia: a door-to-door survey

OBJECTIVE

To carry out a door-to-door survey in rural areas of the Cordillera Province, Santa Cruz Department, Bolivia, to determine the prevalence of neurologic diseases (epilepsy, stroke, parkinsonism, and peripheral neuropathy) in a sample of approximately 10,000 inhabitants.

METHODS

A team of nondoctor health workers administered a standard screening instrument for neurologic diseases-a slightly modified version of the World Health Organization protocol. All subjects found positive during the screening underwent a neurologic examination.

RESULTS

On screening, the authors found 1,130 positive subjects, of whom 1,027 were then investigated by neurologists. On the basis of the definition proposed by the International League Against Epilepsy, we detected 124 epileptic patients (prevalence, 12.3/1,000), 112 of whom had active epilepsy (prevalence, 11.1/1,000) on the prevalence day (November 1, 1994). Peak age-specific prevalence occurred in the 15 to 24-year age group (20.4/1,000). Sex-specific prevalence was higher in women (13.1/1,000) than men (11.4/1,000). Eighty-nine patients (71.8%) underwent a standard EEG recording. Considering both EEG and clinical data, partial seizures were the most common type (53.2%) based on the classification of the International League Against Epilepsy. The mean age at onset was 20.7 years for partial seizures and 13.6 years for generalized seizures. Only 10.5% of patients had received specific treatment for more than 2 months of their life.

CONCLUSION

This report on epilepsy prevalence in Bolivia confirms that epilepsy is a major health problem in rural areas of developing countries.

Mansonella ozzardi infection in Bolivia: prevalence and clinical associations in the Chaco region

A cross-sectional survey carried out in the Chaco region of Bolivia showed that 26% (77 of 296) and 0.7% (2 of 298) of the rural population of the Camiri and Villa Montes areas, respectively, harbored Mansonella ozzardi microfilariae (mf). No significant differences were observed between sexes. The lowest prevalence (9%) was in the 0-14-year-old age group, with no children <11 months of age infected. The prevalence increased sharply in the 25-34-year-old age group (32%), and continued increasing in the older age classes. Microfilaremia, ranging from 1 to 305 mf/20 microl of blood, was lowest in 0-14-year-old children (geometric mean concentration = 1.1 mf/20 microl), and increased with age (>100 mf/20 microl in people >44 years old). An expected increasing sensitivity with the blood volume examined was observed. No significant association between clinical symptoms (fever, skin rash, pruritus, headache, lymphedema, elephantiasis, and articular pain) and microfilaremia was observed.

Prevalence of antibodies against hepatitis A and E viruses among rural populations of the Chaco region, south-eastern Bolivia

We conducted a cross-sectional study to determine the seroprevalence of antibodies against hepatitis A and hepatitis E viruses (HAV and HEV) in the population of two rural areas, Camiri and Villa Montes, of the Chaco region, south-eastern Bolivia. HAV antibodies were detected in 461 (94.1%) of 490 serum samples tested, not differing significantly between sexes and study areas. The HAV seropositivity rate (64.7%) was high even in the youngest age group (1-5 years). The prevalence of HEV was 7.3%, with no significant differences between sexes. The prevalence of HEV antibodies in the population of the Camiri area (10.4%) was significantly higher than in the Villa Montes area (4.4%), possibly due to the better quality of drinking water in the Villa Montes area. In the population </= 30 years of age, the HEV seropositivity rate (4.4%) was significantly lower than in the >/= 31 year-old group. This is consistent with findings in other countries. This is the first report of the prevalence of HEV infection in Bolivia.

In vivo comparison of CHX-DTPA ligand isomers in athymic mice bearing carcinoma xenografts

Monoclonal antibodies (MAbs) labeled with radiometallonuclides via metal chelators are being investigated in the laboratory for use in clinical trials. The biodistribution of 111In- and 88Y-labeled antibody (MAb B72.3) using two isomeric forms (CHX-A and CHX-B) of the 2-(p-isothiocyanatobenzyl)-cyclohexyl-DTPA was compared in athymic mice bearing LS-174T tumors, human colon carcinoma xenografts. CHX-(A or B)-125I-DTPA-B72.3 was co-injected in all athymic mice to assess if the chelate conjugation altered the properties of MAb B72.3. In vitro studies demonstrated maintenance of integrity and immunoreactivity for both radioimmunoconjugates. The in vivo analysis, however, indicated major differences between the two isomer forms. In fact, the 88Y-CHX-A-DTPA radioimmunoconjugate demonstrated over the 7-day study period, a more efficient and stable tumor localization as well as a slower blood clearance rate than the CHX-B-DTPA chelate conjugate, suggesting a greater in vivo stability. Differences were also evident in critical normal organ uptake: no significant increase in liver- and spleen- or bone-to-blood ratios was observed when the CHX-A-DTPA chelate was labeled with indium or yttrium. The results described here demonstrate that the CHX-A-DTPA chelate conjugate can be considered more suitable than the CHX-B-DTPA isomer form when radiometallonuclides are coupled to an MAb.

Differential expression of a new tumor-associated antigen, TLP, during human colorectal cancer tumorigenesis

Tumour liberated particles (TLP) have been proposed as a potential new serum tumor marker. In particular, a high percentage of patients with early stages of lung cancer scored positive for serum TLP, suggesting its possible role as a marker for early diagnosis of disease. The aim of the present study was to analyze the expression of TLP in the colorectal adenoma-carcinoma sequence in order to determine whether its expression correlates with the various stages of cancer transformation. TLP distribution was assessed by immunohistochemistry in normal, premalignant, and malignant colorectal lesions. Normal colonic mucosa and hyperplastic polyps showed no positive staining, whereas adenomas and adenocarcinomas reacted to anti-TLP serum. The percentage of positive tumor cells increased from adenomas with mild dysplasia to adenomas with severe dysplasia. Moreover, a supranuclear staining pattern was observed mainly in adenomas with mild dysplasia, whereas adenomas with severe dysplasia as well as adenocarcinomas showed a characteristic diffuse staining pattern and a strong staining intensity. Only a few cases of adenocarcinoma were found to be TLP-negative and all were poorly differentiated. Our results suggest that TLP antigen expression may be considered as a marker of epithelial atypia in the colorectal tract and as a potential target for new diagnostic and/or therapeutic approaches to human colorectal cancer.

Evaluation of the CA 242 tumor antigen as a potential serum marker for colorectal cancer

OBJECTIVE

The present study was designed to define the performance of serum CA 242 as a marker in colorectal cancer patients.

PATIENTS AND METHODS

Serum samples from 1,013 subjects (440 healthy volunteers, 384 patients with primary or recurrent colorectal carcinoma and 189 with benign colorectal diseases) were evaluated.

RESULTS

The measurement of serum CA 242 levels in the population of healthy subjects demonstrated the presence of positive levels in approximately 5% of the cases. Interestingly, similar results (5.8%) were obtained in patients with benign colorectal disease, demonstrating the high specificity of CA 242. When serum samples from colorectal cancer patients were analyzed, a sensitivity of 34.9% was observed. Moreover, 18.6% Stage A and B patients had positive CA 242 levels, compared to 33.3% and 58.8% of Stage C and D patients, respectively, indicating a correlation with the stage of disease. A comparison between preoperative and immediate postoperative CA 242 levels showed a consistent relationship between the efficacy of surgery and the reduction in serum CA 242 levels; further, elevated CA 242 levels were present in the immediate postsurgical follow-up of patients undergoing palliative surgery. A longitudinal evaluation of serum CA 242 levels demonstrated that this marker was indicative of the status of disease.

CONCLUSIONS

The results obtained suggest the possible utility of CA 242 in monitoring the disease status, providing a rationale for future studies focusing on the longitudinal monitoring of colorectal cancer patients.

[Antibodies against Trichinella spiralis in the rural population of the Province of Cordillera, Bolivia]

A seroepidemiological study was conducted to determine the prevalence of antibodies to Trichinella spiralis among rural residents of Cordillera province, Santa Cruz Department, Bolivia. Using the enzyme-linked immunosorbent assay (ELISA), 234 serum samples were examined, and antibodies were detected in seven of the samples (3%). The results document for the first time the presence of human infestation with Trichinella in Bolivia and suggest the need to strengthen trichinelosis surveillance in the municipal slaughterhouses, to prevent the clandestine slaughter of animals, and particularly to ensure that residents and meat producers in the area become aware of the dangers of this zoonosis.

Novel clinical approaches in monoclonal antibody-based management in colorectal cancer patients: radioimmunoguided surgery and antigen augmentation

Surgery, the most effective treatment for colon and rectal cancer, is based on empirical knowledge of the patterns of tumor spread, gross findings at laparotomy, and histologic confirmation of tumor-free margins. In spite of the many technical improvements in surgery, there has not been a significant change in cure rates for colon and rectal cancers. In fact, one-half of affected patients will not survive 5 years. It is in this arena of treatment for primary colon and rectal cancer patients that radioimmunoguided surgery (RIGS) technology may provide the most benefit. RIGS is an intraoperative procedure for detection of carcinoma lesions that are targeted with a radiolabeled monoclonal antibody (MAb) to provide the surgeon with immediate intraoperative definition of tumor margins and identification of occult disease. To optimize this technique, our studies were designed to increase tumor uptake by higher affinity CC-49 (a second-generation MAb) and to increase tumor antigen expression using biological response modifiers (BRMs). The ability of BRMs, such as interferons (IFNs), to enhance the expression of tumor-associated antigens, may play an important role in an adjuvant setting for MAb-based treatment. Preclinical and clinical data provided evidence for the use of IFN as an adjuvant to enhance MAb-targeting of human carcinoma lesions. A combination protocol with IFN and RIGS is ongoing at our institution.

Novel clinical approaches in monoclonal antibody-based management in colorectal cancer patients: radioimmunoguided surgery and antigen augmentation

Surgery, the most effective treatment for colon and rectal cancer, is based on empirical knowledge of the patterns of tumor spread, gross findings at laparotomy, and histologic confirmation of tumor-free margins. In spite of the many technical improvements in surgery, there has not been a significant change in cure rates for colon and rectal cancers. In fact, one-half of affected patients will not survive 5 years. It is in this arena of treatment for primary colon and rectal cancer patients that radioimmunoguided surgery (RIGS) technology may provide the most benefit. RIGS is an intraoperative procedure for detection of carcinoma lesions that are targeted with a radiolabeled monoclonal antibody (MAb) to provide the surgeon with immediate intraoperative definition of tumor margins and identification of occult disease. To optimize this technique, our studies were designed to increase tumor uptake by higher affinity CC-49 (a second-generation MAb) and to increase tumor antigen expression using biological response modifiers (BRMs). The ability of BRMs, such as interferons (IFNs), to enhance the expression of tumor-associated antigens, may play an important role in an adjuvant setting for MAb-based treatment. Preclinical and clinical data provided evidence for the use of IFN as an adjuvant to enhance MAb-targeting of human carcinoma lesions. A combination protocol with IFN and RIGS is ongoing at our institution.

In vivo evaluation of a lead-labeled monoclonal antibody using the DOTA ligand

The aim of this study was to assess the utility of a radioimmunoconjugate containing a lead radionuclide for therapy and scintigraphy applications. The radioimmunoconjugate evaluated consisted of a bifunctional DOTA ligand and monoclonal antibody (MAb) B72.3 using athymic mice bearing LS-174T tumors, human colon carcinoma xenografts. In the studies reported here, the lead-203-DOTA complex itself was first demonstrated to have in vivo stability. MAb B72.3 was then conjugated with the DOTA ligand and labeled with 203Pb, and the immunoreactivity of B72.3 was maintained. The localization of the radioimmunoconjugate to tumor tissue and other select organs paralleled that of DOTA-125I-B72.3, suggesting a similar metabolic pattern of the two radioimmunoconjugates. Thus, the DOTA-metal complex does not alter the behavior of the radioimmunoconjugate. Tumor localization of the 203Pb-DOTA-B72.3 conjugate was demonstrated with biodistribution studies as well as immunoscintigraphy studies. Such data highlight the stability of a lead radionuclide in the DOTA ligand. The suitability of this chelation chemistry for labeling radioimmunoconjugates with a lead radionuclide now makes its application in nuclear medicine a feasible proposition.

Patterns of antimicrobial use and antimicrobial resistance among healthy children in Bolivia

OBJECTIVE

To determine the incidence of antimicrobial-resistant, nonpathogenic Escherichia coli among healthy children aged 6-72 months in Camiri town and a rural village, Javillo, in south-eastern Bolivia.

METHOD

A community-based survey: stool samples were obtained from 296 healthy children selected by modified cluster sampling in Camiri and all 25 eligible children in Javillo. E. coli isolates were tested for antimicrobial susceptibility according to the standard disc diffusion method. By a questionnaire survey of 12 pharmacies and by using simulated patients, we investigated the antimicrobial availability and the usage patterns in Camiri town.

RESULTS

In Camiri, over 90%, and in Javillo over 70% of children carried E. coli resistant to ampicillin, trimethoprim-sulphamethoxazole (TMP/SMX) or tetracycline. Overall, 63% of children carried E. coli with multiple resistance to ampicillin, TMP/SMX, tetracycline and chloramphenicol. In the simulated patients study, antimicrobials were dispensed inappropriately for 92% of adults and 40% of children with watery diarrhoea, and were under-prescribed for males with urethral discharge (67%) or females with fever and dysuria (58%). The dose and/or duration of antimicrobials dispensed was almost always too low.

CONCLUSION

Our study showed a disturbingly high prevalence of carriage of nonpathogenic E. coli resistant to antimicrobials. The prevalence of resistance to ampicillin and TMP/SMX was higher than that previously reported in developing countries. The existence of a large reservoir of resistance genes in healthy individuals in developing countries represents a threat to the success of antimicrobial therapy throughout the world. Programmes to improve rational and effective drug use in developing countries are urgently needed.

Response to measles revaccination among Bolivian school-aged children

The response to measles revaccination was evaluated in 1994 among 202 Bolivian school-aged children whose antibody levels were below 200 miu (milli-international units) by haemagglutination inhibition (HI) in a large-scale serosurvey conducted in Santa Cruz one year earlier. Of the 202 revaccinated children, 164 (82%) had seroconverted between the 1993 serosurvey and the pre-revaccination blood sample. A measles outbreak occurred in Santa Cruz 6 months before the revaccination. Among the seroconvertors, only 6% gave a history of measles, and 15% a history of contact with a case of measles. All 20 children with undetectable HI antibody pre-revaccination, and all 6 children with levels below 100 miu, seroconverted after revaccination. The geometric mean titres by HI at 4 weeks after revaccination were 2018 miu (95% confidence limits [95% CL] 1143, 3564) and 398 miu (95% CL 254, 625) in the 2 groups, respectively. Six of 9 children with pre-revaccination antibody titres of 100-199 miu also seroconverted. No child demonstrated a measles-specific immunoglobulin M response. Among the 29 children who seroconverted and were followed up at one year after revaccination, 15(52%) showed a fourfold or greater decline in antibody levels, which in 8 fell to levels below 200 miu. This study confirmed the observation that revaccination is successful in producing an antibody response in children with low or undetectable pre-revaccination titres, but it also confirmed that vaccine-induced immunity wanes rapidly.

Quantitative analysis of CEA expression in colorectal adenocarcinoma and serum: lack of correlation

Tissues and sera from 110 patients diagnosed with colorectal primary carcinoma, 20 patients with benign colorectal diseases and 31 healthy donors were subjected to quantitative CEA analysis. Multiple samples from tumor lesions and autologous histologically normal mucosa (10 cm from the tumor) were obtained at the time of surgery (cancer patients) or endoscopy (benign patients and healthy volunteers). CEA content was measured in protein extracts obtained from these tissues using a quantitative RIA method. A limit of normality for CEA content was established as 300 ng/mg of protein. When this was taken as cut-off, 104 of 110 (94.5%) tumor lesions and 51 of 110 (46.4%) autologous histologically normal colonic mucosa from cancer patients had elevated CEA levels. No correlation with stage of disease was found, while a correlation was observed with degree of tumor differentiation. A statistically significant difference between CEA content in tumor lesions and in histologically normal mucosa from cancer patients was observed (p = -0.001). Moreover, CEA content was statistically higher in the normal mucosa from cancer patients than in that from healthy donors (p = 0.005). CEA content in tissue specimens from benign lesions differed significantly from that in tissue from healthy donors (p = 0.005) and in carcinoma lesions (p < 0.001). The highest CEA content was observed in benign lesions with severe dysplasia. No statistical correlation between CEA content in carcinoma tissues and serum CEA levels (r = 0.195, p = .13) was found. Therefore, in considering diagnosis or therapy with anti-CEA MAbs for colorectal-carcinoma patients, or potential therapies with anti-CEA recombinant vaccines, serum CEA levels should not be taken as indicating CEA expression in tumor lesions.