Reply to 'preoperative PET/CT in early-stage breast cancer: is the TNM classification enough?'

18F-FDG-PET/CT for systemic staging of patients with newly diagnosed ER-positive and HER2-positive breast cancer

OBJECTIVES

This study assesses ¹⁸F-FDG-PET/CT for patients with newly diagnosed estrogen receptor-positive/human epidermal growth factor receptor-negative (ER+/HER2-) and human epidermal growth factor receptor-positive (HER2+) breast cancer.

METHODS

In this Institutional Review Board-approved retrospective study, our Healthcare Information System was screened for patients with ER+/HER2- and HER2+ breast cancer who underwent ¹⁸F-FDG-PET/CT prior to systemic or radiation therapy. The initial stage was determined from mammography, ultrasound, magnetic resonance imaging, and/or surgery.¹⁸F-FDG-PET/CT was evaluated to identify unsuspected extra-axillary regional nodal and distant metastases. The proportion of patients upstaged overall and stratified by stage and receptor phenotypes was calculated along with confidence intervals (CI).

RESULTS

A total of 238 patients with ER+/HER2- and 245 patients with HER2+ who met inclusion criteria were evaluated. For patients with ER+/HER2-breast cancer, ¹⁸F-FDG-PET/CT revealed unsuspected distant metastases in 3/71 (4%) initial stage IIA, 13/95 (14%) stage IIB, and 15/57 (26%) stage III. For patients with HER2+ breast cancer, ¹⁸F-FDG-PET/CT revealed unsuspected distant metastases in 3/72 (4%) initial stage IIA, 13/93 (14%) stage IIB, and 13/59 (22%) stage III. The overall upstaging rate for IIB was 14% (95% confidence interval (CI): 9-20%).

CONCLUSIONS

¹⁸F-FDG-PET/CT revealed distant metastases in 14% (95% CI: 9-20%) of patients with stage IIB ER+/HER2- and HER2+ breast cancer, which is similar to upstaging rates previously seen in patients with stage IIB triple-negative breast cancer (15%, 95% CI: 9-24%). The detection of unsuspected distant metastases in these patients alters treatment and prognosis. NCCN guidelines should consider adding patients with stage IIB breast cancer for consideration of systemic staging with ¹⁸F-FDG-PET/CT at the time of initial diagnosis.

(18)F-FDG-PET/CT for systemic staging of newly diagnosed triple-negative breast cancer

PURPOSE

National Comprehensive Cancer Network guidelines recommend (18)F-FDG-PET/CT, in addition to standard staging procedures, for systemic staging of newly diagnosed stage III breast cancer patients. However, factors in addition to stage may influence PET/CT utility. As breast cancers that are negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor (triple-negative breast cancer, or TNBC) are more aggressive and metastasize earlier than other breast cancers, we hypothesized that receptor expression may be one such factor. This study assesses (18)F-FDG-PET/CT for systemic staging of newly diagnosed TNBC.

METHODS

In this Institutional Review Board-approved retrospective study, our Healthcare Information System was screened for patients with TNBC who underwent (18)F-FDG-PET/CT in 2007-2013 prior to systemic or radiation therapy. Initial stage was determined from mammography, ultrasound, magnetic resonance imaging, and/or surgery, if performed prior to (18)F-FDG-PET/CT. (18)F-FDG-PET/CT was evaluated to identify unsuspected extra-axillary regional nodal and distant metastases, as well as unsuspected synchronous malignancies. Kaplan Meier survival estimates were calculated for initial stage IIB patients stratified by whether or not stage 4 disease was detected by (18)F-FDG-PET/CT.

RESULTS

A total of 232 patients with TNBC met inclusion criteria. (18)F-FDG-PET/CT revealed unsuspected distant metastases in 30 (13 %): 0/23 initial stage I, 4/82 (5 %) stage IIA, 13/87 (15 %) stage IIB, 4/23 (17 %) stage IIIA, 8/14 (57 %) stage IIIB, and 1/3 (33 %) stage IIIC. Twenty-six of 30 patients upstaged to IV by (18)F-FDG-PET/CT were confirmed by pathology, with the remaining four patients confirmed by follow-up imaging. In addition, seven unsuspected synchronous malignancies were identified in six patients. Initial stage 2B patients who were upstaged to 4 by (18)F-FDG-PET/CT had significantly shorter survival compared to initial stage 2B patients who were not (3-year Kaplan Meier estimate 0.33, 95 % CI 0.13-0.55 versus 0.97, CI 0.76-0.93, p < .0001).

CONCLUSION

F-FDG-PET/CT revealed distant metastases in 15 % of patients with stage IIB TNBC. Stage IIB patients upstaged to 4 by (18)F-FDG-PET/CT had significantly shorter survival than those who were not, consistent with (18)F-FDG-PET/CT detecting an increased burden of disease. This study provides further evidence that populations of patients with stage IIB breast cancer, such as TNBC, should be considered for systemic staging with (18)F-FDG-PET/CT at the time of initial diagnosis.

Retrospective analysis of 18F-FDG PET/CT for staging asymptomatic breast cancer patients younger than 40 years

National Comprehensive Cancer Network guidelines consider (18)F-FDG PET/CT for only clinical stage III breast cancer patients. However, there is debate whether TNM staging should be the only factor in considering if PET/CT is warranted. Patient age may be an additional consideration, because young breast cancer patients often have more aggressive tumors with potential for earlier metastases. This study assessed PET/CT for staging of asymptomatic breast cancer patients younger than 40 y.

METHODS

In this Institutional Review Board-approved retrospective study, our hospital information system was screened for breast cancer patients younger than 40 y who underwent staging PET/CT before any treatment. Patients with symptoms or conventional imaging findings suggestive of distant metastases or with prior malignancy were excluded. Initial stage was based on physical examination, mammography, ultrasound, and breast MR imaging. PET/CT was then evaluated to identify unsuspected extraaxillary regional nodal and distant metastases.

RESULTS

One hundred thirty-four patients with initial breast cancer stage I to IIIC met inclusion criteria. PET/CT findings led to upstaging to stage III or IV in 28 patients (21%). Unsuspected extraaxillary regional nodes were found in 15 of 134 patients (11%) and distant metastases in 20 of 134 (15%), with 7 of 134 (5%) demonstrating both. PET/CT revealed stage IV disease in 1 of 20 (5%) patients with initial clinical stage I, 2 of 44 (5%) stage IIA, 8 of 47 (17%) stage IIB, 4 of 13 (31%) stage IIIA, 4 of 8 (50%) stage IIIB, and 1 of 2 (50%) stage IIIC. All 20 patients upstaged to stage IV were histologically confirmed. Four synchronous thyroid and 1 rectal malignancies were identified.

CONCLUSION

PET/CT revealed distant metastases in 17% of asymptomatic stage IIB breast cancer patients younger than 40 y. Although guidelines of the National Comprehensive Cancer Network recommend against systemic staging in patients with stage II disease, our data suggest that PET/CT might be valuable in younger patients with stage IIB and III disease. Use of PET/CT in younger patients has the potential to reduce the morbidity and cost of unnecessary therapies in young breast cancer patients.