In women who have locally advanced breast cancer (LABC), staging defines the extent of the disease and guides therapy.
Researchers have found in the first large, randomized, controlled study on the subject that 18 F-labeled fluorodeoxyglucose positron emission tomography–computed tomography (PET-CT) finds more distant metastases and allows more accurate staging than usual staging, which is determined by a bone scan and computed tomography (CT) of the thorax/abdomen and pelvis.
Findings of the study, led by Ian S. Dayes, MD, MSc, with the department of oncology at McMaster University in Hamilton, Ont., were published online in the Journal of Clinical Oncology.
Scans indicate less aggressive treatment strategy
The authors of the new study wrote that women with LABC, who are at high risk of metastatic disease, have large tumors that “can involve the chest wall or skin, clinically fixed axillary lymph nodes, or infraclavicular, supraclavicular, or internal mammary lymphadenopathy.”
If staging does not detect metastases, treatment is centered on combined modality therapy with curative intent (neoadjuvant chemotherapy and surgery, followed by regional radiation). If metastases are found, the treatment goal changes to controlling the disease.
In this study, twice as many women saw their stage increase from stage IIB or III to stage IV when PET-CT was used instead of conventional staging, guiding their treatment toward less aggressive care to control, rather than attempt to cure, the disease.
The women included in this study had histological evidence of invasive ductal carcinoma of the breast and TNM stage III or IIb (T3N0, but not T2N1).
Methods and results
Between December 2016 and April 2022, consenting patients from six regional cancer centers in Ontario were randomly assigned to one of two groups: 184 patients were randomly assigned to whole-body PET-CT and 185 patients to conventional staging.
Overall, the authors wrote, 43 (23%) of PET-CT patients “were upstaged” to stage IV compared with 21 (11%) of the conventionally staged patients (relative risk, 2.4; 95% confidence interval [CI], 1.4-4.2, P = .002).
There were 33 patients in a subset with inflammatory breast cancer and, among them, 4 of 16 (25%) PET-CT patients were upstaged to stage IV compared with 4 of 17 (24%) conventionally staged patients.
In the patients who did not have inflammatory breast cancer, 39 of 168 (23%) PET-CT patients were upstaged compared with 17 (10%) of 168 in the conventionally staged group.
Journal of Clinical Oncology (JCO) Senior Deputy Editor Kathy D. Miller, MD, said that, “PET/CT staging identifies distant disease in more patients and changes goals of therapy. Further research is needed to determine the impact on patient outcome.”