A 37-year-old woman was diagnosed with bilateral synchronous invasive
lobular breast cancer, ER/PR-positive and HER-2/neu negative. Her
initial mammogram showed a 2.5-cm mass in the left breast and 1.5-cm axillary
lymph node. On PET/CT there was 2.3-cm left subareolar enhancing mass with an
standardized uptake value of 7.7, 1.5-cm left axillary lymph node with an
standardized uptake value of 5.3 with no evidence of distant metastasis. MRI
breast showed 3.5 × 3.5 cm, 1 × 0.8 cm and 1.3 cm masses in the
upper outer quadrant of left breast and 3.5 × 2 cm mass in the upper
inner quadrant of right breast. The patient received neoadjuvant chemotherapy
with four cycles of dose-dense doxorubicin and cyclophosphamide followed by
four cycles of dose-dense paclitaxel with good clinical response.
On repeat MRI of the breast there was interval decrease in size to 1.5
× 0.8 cm, with resolution of two other masses in upper outer quadrant of
left breast and minimal enhancement in the right breast. PET/CT showed no
discrete mass or uptake in the breast with no evidence of distant metastasis.
The patient underwent bilateral mastectomy and axillary lymph node dissection.
The right mastectomy specimen showed no residual disease and right axillary
lymph nodes were negative. However, in the left mastectomy specimen there was a
2.5-cm poorly differentiated residual invasive carcinoma with ductal and
lobular features and two of the left axillary lymph nodes were positive for
involvement with malignancy.
Munir Ghesani, MD, is an Associate Clinical Professor of Radiology at
Columbia University College of Physicians and Surgeons and Attending
Radiologist at St. Lukes-Roosevelt Hospital Center.
Vamsee Torri, MD, is a fellow in Hematology/Oncology at St.
Lukes-Roosevelt Hospital Center.
1: Axial CT, PET, coregistered PET and CT images at the level of breast parenchyma as well as maximal intensity projection images demonstrate symmetric low-grade metabolic activity in breast parenchyma bilaterally, which may be merely physiologic in this premenopausal patient. There is no obvious asymmetric soft tissue mass or abnormal focal hypermetabolic activity.
2: Axial CT, PET, coregistered PET and CT images at the level of axilla do not demonstrate any asymmetric axillary lymphadenopathy or focal abnormal hypermetabolic activity. There are bilateral axillary lymph nodes which do not meet radiographic criteria for significance. In addition, these lymph nodes demonstrate preserved fatty hilum; low-grade metabolic activity associated with these lymph nodes is often benign, such as in the setting of reactive hyperplasia.
3: Axial, coronary and sagittal PET images as well as MIP PET images demonstrate prominent metabolic activity in the bone marrow, which, given the clinical context, is most consistent with chemotherapy effect.
Source: M Ghesani
PET/CT is shown to detect metastatic lesions and identify equivocal
lesions on conventional imaging. In breast cancer, FDG PET has been used for
defining the extent of recurrent or metastatic disease. FDG PET modality of
imaging has 88% sensitivity and 80% specificity for primary breast lesion, 61%
sensitivity and 80% specificity for axillary metastases, and 93% sensitivity
and 79% specificity for metastatic disease. Serial FDG PET has been widely
studied during the neoadjuvant treatment of locally advanced breast cancer with
a significant standardized uptake value uptake difference; standardized uptake
value did not vary much in nonresponders (based on pathology findings) but was
markedly decreased to background levels in 94% of responders. The sensitivity
to detect malignant lesions decreases with low grade tumors and lesions <1
cm. PET/CT and breast MRI should complement each other for treatment planning
in this subgroup.
The above case and discussion illustrate the possibility of false
negativity of PET/CT after neoadjuvant therapy, as microscopic and sometimes
gross residual disease may still be present. These false negative findings are
more likely to occur in lobular carcinoma, given relatively lower accuracy of
FDG PET imaging in this subtype of breast carcinoma when compared to ductal
carcinoma. It is likely that improvement in PET/CT technology, introduction of
specific biomarkers for imaging (including specific markers for cellular
proliferation) and advances in MRI techniques may further improve accuracy of
imaging modalities for detection of residual breast carcinoma after neoadjuvant
For more information:
- Rosen EL, Eubank WB, Mankoff DA. FDG PET, PET/CT, and breast cancer
imaging. Radiographics. 2007;27 Suppl1:S215-S229.
- Rousseau C, Devillers A, Sagan C, et al. Monitoring of early
response to neoadjuvant chemotherapy in stage II and III breast cancer by [18F]
fluorodeoxyglucose positron emission tomography. J Clin Oncol.
- Kumar R, Chauhan A, Zhuang H, et al. Clinicopathologic factors
associated with false negative FDG-PET in primary breast cancer. Breast
Cancer Res Treat. 2006;98:267-274.
- Iagaru A, Masamed R, Silberman H, et al The role of F-18 FDG PET/CT
and breast MRI in the management of breast cancer. J Clin Oncol.