Implications of different CA 15-3 levels according to breast cancer subtype at initial diagnosis of recurrent or metastatic breast cancer

Detection of secondary metastatic breast cancer by measurement of plasma CA 15.3

BACKGROUND

Most current guidelines do not recommend the serial analysis of tumour marker CA 15.3 in the follow-up of asymptomatic patients treated for early breast cancer (EBC). These guidelines are based on small-scale studies carried out in an era with more limited treatment options than today. In our large academic centre, serial measurements of CA 15.3 are used routinely in the follow-up of EBC, whereas imaging for distant metastases is only carried out on indication.

PATIENTS AND METHODS

In this retrospective single-centre study, patients were included if they were treated for EBC between 1 January 2000 and 1 January 2018, diagnosed with secondary metastatic disease at least 6 months after initial surgery and had CA 15.3 available at the time of diagnosis of metastases. The primary objective was to evaluate the proportion of patients in whom metastatic disease was discovered by an increasing CA 15.3. Information on the method of metastases detection, CA 15.3 evolution and survival was collected after approval of the ethics committee.

RESULTS

At the moment of diagnosis of metastases, 451 of 730 included patients (62%) had CA 15.3 levels above the upper limit of normal (>30 kU/l). In 269 patients (37%), an increasing CA 15.3 was the first sign that led to the diagnosis of metastases. This was most frequent in luminal A-like tumours (48%) and in liver (45%) and bone (41%) localisation of metastases. By contrast, reported symptoms triggered the diagnosis of metastatic disease in 48% of the patients. Median overall survival was significantly longer when the relapse was discovered by CA 15.3 elevation versus those discovered by another trigger (abnormal clinical examination or history, abnormal laboratory tests or an incidental finding) (35 versus 22 months; P = 0.0027).

CONCLUSION

When CA 15.3 is systematically used in the follow-up of EBC patients, the diagnosis of metastatic disease is made in 37% by a CA 15.3 increase.

Correlation between salivary and serum CA15-3 concentrations in patients with breast cancer

The early detection of breast cancer enables the use of less aggressive treatment and increases patient survival. The transmembrane glycoprotein mucin 1, which is also known as cancer antigen 15-3 (CA15-3), is aberrantly glycosylated and overexpressed in a variety of epithelial cancers, and serves a crucial role in the progression of the disease. CA15-3 is currently used as a marker of breast cancer. In the present study, CA15-3 concentrations in saliva and blood of patients with breast cancer were evaluated to test new assays to detect salivary CA15-3 in addition to ELISA and its diagnostic value. To the best of our knowledge, there are no previous reports of the use of chemiluminescence assay (CLIA) and electrochemiluminescence assay (ECLIA) in saliva. Saliva and blood were collected on the same day from patients with breast cancer (n=26) and healthy controls (n=28). For each subject, the level of serum CA15-3 was measured using ECLIA, and the level of salivary CA15-3 was measured using ECLIA, CLIA and enzyme-linked immunosorbent assay (ELISA). ELISA and CLIA were able to detect CA15-3 in saliva; however, ECLIA could not detect salivary CA15-3. There was no significant difference between the mean serum and salivary CA15-3 levels in patients with breast cancer or healthy controls. The levels of CA15-3 were highest for luminal breast cancer subtypes and stage IV cases. A moderate correlation was observed between salivary and serum CA15-3 levels as measured by ELISA in breast cancer patients (r=0.56; P=0.0047). The results demonstrated that ECLIA was not a good method to detect salivary CA15-3, although it is the gold standard for detecting serum CA15-3. The presence of CA15-3 in saliva was confirmed, and this will be useful in future research. Further investigations are necessary to confirm the ability to detect salivary CA15-3 and its correlation with serum CA15-3.

CA 15.3 measurements for separating FDG PET/CT positive from negative findings in breast carcinoma recurrence

In breast cancer CA 15.3 is considered the tumour marker of choice. CA 15.3 is directly related to the disease extent and to hormone status (estrogen receptor ER+/ ER-, progesterone receptor PR+/PR-). This study was designed to assess the impact of disease extent, hormone receptor and HER2-status, and circulating blood volume on the area-under the ROC-curve of CA 15.3 to separate FDG PET positive from negative findings. Patients, methods: We retrospectively evaluated 379 FDG PET/CT examinations performed in 80 patients with breast cancer. Blood volumes were derived using the formulas by Nadler and multiplied by their corresponding CA 15.3 measurement. Results: ROC-curve analysis revealed an AUC of 0.695 (p = 0.0001) for CA 15.3 to separate FDG PET positive from negative findings. AUC measurements to separate normal scan find-ings from loco-regional disease and meta- static disease were 0.527 (p = 0.587) and 0.732 (p = 0.0001), respectively. AUC measurements for CA 15.3 to separate positive from negative FDG PET findings, in ER+ and ER- patients, were respectively 0.772 (p = 0.0001) and 0.596 (p = 0.143). AUC measurements for CA 15.3 to separate positive from negative FDG PET findings, in PR+ and PR- patients, were respectively 0.675 (p = 0.0001) and 0.694 (p = 0.0001). In HER2-positive and -negative patients, the AUC measurements were respectively 0.594 (p = 0.178) and 0.701 (p = 0.0001) to separate positive from negative FDG PET findings. Conclusion: The AUC for CA 15.3 measurements to separate FDG PET positive from negative findings in breast cancer patients with suspected recurrence proved to be directly related to the extent of the recurrent disease and hormone receptor status and inversely related to HER2-status. Correcting CA 15.3 measurements for blood volumes did not impact the AUC.

Cancer-associated carbohydrate antigens for clinical diagnostic markers--its effectiveness and limitations

Cancer cells express various aberrant glycoconjugates. Several kinds of carbohydrate antigens have been used for the serological tumor markers. In particular, the serological level of sialylated carbohydrate antigens, which contain the sialic acid residue in their structure, showed effectiveness in diagnosing cancer behavior. Although large number of carbohydrate antigens in serum of cancer patients was elevated broadly in various cancers, each tumor marker has different sensitivity and specificity for each cancer. Therefore, the combined use of several tumor markers which have different characteristics is effective for better sensitivity in diagnosing cancer behavior. The mechanism of synthesizing cancer-associated carbohydrate antigens is not fully understood because it is very complex. In addition, new cancer-associated carbohydrate antigens are also identified by molecular oncological studies. Those investigations are considered to develop more effective tumor markers to diagnose cancer behavior.

MUC1 and metastatic cancer: expression, function and therapeutic targeting

MUC1 is a transmembrane mucin that is often overexpressed in metastatic cancers and often used as a diagnostic marker for metastatic progression. The extracellular domain of MUC1 can serve as a ligand for stromal and endothelial cell adhesion receptors, and the cytoplasmic domain engages in several interactions that can result in increased migration and invasion, as well as survival. In this review, we address the role of MUC1 in metastatic progression by assessing clinical studies reporting MUC1 levels at various disease stages, reviewing mouse models utilized to study the role of MUC1 in metastatic progression, discuss mechanisms of MUC1 upregulation, and detail MUC1 protein interactions and signaling events. We review interactions between MUC1 and the extracellular environment, with proteins colocalized in the plasma membrane and/or cytoplasmic proteins, and summarize the role of MUC1 in the nucleus as a transcriptional cofactor. Finally, we review recent publications describing current therapies targeting MUC1 in patients with advanced disease and the stage of these therapies in preclinical development or clinical trials.

Targeted imaging of breast tumor progression and therapeutic response in a human uMUC-1 expressing transgenic mouse model

The ability to monitor breast cancer initiation and progression on the molecular level would provide an effective tool for early diagnosis and therapy. In the present study, we focused on the underglycosylated MUC-1 tumor antigen (uMUC-1), which is directly linked to tumor progression from pre-malignancy to advanced malignancy in breast cancer and has been identified as the independent predictor of local recurrence and tumor response to chemotherapy. We investigated whether changes in uMUC-1 expression during tumor development and therapeutic intervention could be monitored non-invasively using molecular imaging approach with the uMUC-1-specific contrast agent (MN-EPPT) detectable by magnetic resonance and fluorescence optical imaging. This was done in mice that express human uMUC-1 tumor antigen (MMT mice) and develop spontaneous mammary carcinoma in a stage-wise fashion. After the injection of MN-EPPT there was a significant reduction in average T2 relaxation times of the mammary fat pad between pre-malignancy and cancer. In addition, T2 relaxation times were already altered at pre-malignant state in these mice compared to non-tumor bearing mice. This indicated that targeting uMUC-1 could be useful for detecting pre-malignant transformation in the mammary fat pad. We also probed changes in uMUC-1 expression with MN-EPPT during therapy with doxorubicin (Dox). We observed that tumor delta-T2s were significantly reduced by treatment with Dox indicating lower accumulation of MN-EPPT. This correlated with a lower level of MUC-1 expression in the Dox-treated tumors, as confirmed by immunoblotting. Our study could provide a very sensitive molecular imaging approach for monitoring tumor progression and therapeutic response.