correlation between CA 15.3 and PET/CT evidence of metastatic disease in breast cance

[Lani]

not her2 subtype specific, but important stats, nonetheless:

Curr Radiopharm. 2014 May 15. [Epub ahead of print]

Correlation between Cancer Antigen 15.3 Value and Qualitative and Semi-quantitative Parameters of Positron Emission Tomography/Computed Tomography in Breast Cancer patients.
Cervino AR, Saibene T, Michieletto S, Ghiotto C, Bozza F, Saladini G, Evangelista L1.


Abstract
Background. The association of PET/CT and tumor markers can be considered complementary, since any significant increases of tumor markers can indicate the presence of disease while PET/CT is able to detect and describe the tumor sites. In this retrospective, single-institution study, we determine the correlation between cancer antigen (CA) 15.3 value and qualitative and semi-quantitative PET/CT data in breast cancer (BC) patients. Methods. 193 BC patients (median age 61 yrs) already treated with primary treatment (surgery and others) were identified through institutional databases. All patients underwent PET/CT for increase in tumor markers, post-therapy evaluation, restaging and doubtful conventional imaging for disease relapse. The CA15.3 values before PET/CT scan were collected for all patients. Clinical outcome was defined as presence or absence of disease recurrence based on follow-up data (histological or imaging findings). CA15.3 quartile values and qualitative and semi-quantitative (maximum Standardized Uptake Value - SUVmax) PET/CT findings were compared with chi-square test and linear regression analysis. Results. The mean value of CA15.3 was significantly higher in patients with positive than negative PET/CT (67.51±120.92 vs. 25.54±17.54, p<0.005). PET/CT was positive in 107 (55%) and negative in 86 (45%) patients; CA15.3 value was considered abnormal (≥ 31 UI/mL) in 85 (44%) patients; 57 of them showed positive PET/CT while 28 a negative scan (67 vs. 33%, p<0.05). In all 193 patients, the disease recurrence was found in 71 (37%), whereas 122 (63%) were disease-free. The diagnostic accuracy of PET/CT in all 193 patients was 74%. Among patients with normal CA15.3 value (n=108), 50 showed positive PET/CT; 24 out of these latter 50 patients (48%) had recurrence of disease. The combination of the highest quartile of CA15.3 (value>45 UI/ml) and FDG PET/CT determined high sensitivity and accuracy (92% and 82%, respectively) but a low specificity (50%) for restaging BC patients. The highest specificity (~ 70%) was found when PET/CT and 2nd quartile of CA15.3 (value: 12.95-25) were associated. No correlation between CA15.3 values and SUVmax was found (p=0.489); whereas a trend in increase of the CA15.3 value and SUVmax in the presence of visceral and no-visceral site of disease (22.4±16.2, 64.9±108 and 6.4±4.2, 8.2±5.1, respectively) was identified. Conclusions. The value of CA15.3 and PET/CT findings are consistently complementary. About 25% of BC patients with a negative CA15.3 value had a positive PET/CT and disease relapse. SUVmax and CA15.3 values are not correlated.
PMID: 24836946