Therapeutic Effects of CDK4/6 Inhibitors in Gastric and Colonic Metastases From Breast Cancer: A Case Report

Abstract

Breast cancer often metastasizes to the lungs, bones, liver, and brain; however, gastric and colonic metastases from breast cancer are rare. Nevertheless, here, we present the case of a 50-year-old woman diagnosed with recurrent breast cancer, exhibiting gastric and colonic metastases that were detected when she experienced intermittent abdominal pain. The differentiation between primary gastric cancer and metastasis from breast cancer was made through immunohistochemical staining. The patient underwent treatment with palbociclib, a cyclin-dependent kinase (CDK)4/6 inhibitor, and anastrozole, with no significant adverse effects. Subsequent upper and lower endoscopic examinations following the initiation of these treatments revealed tumor shrinkage in both gastric and colonic metastases. This case report presents the first instance in which morphological changes in gastrointestinal metastasis induced by CDK4/6 inhibitors could be evaluated.

Keywords: breast cancer; cdk4/6 inhibitor; gastric and colorectal metastases; lobular carcinoma; palbociclib.

Figure 1. Abdominal CT images at diagnosis.

Abdominal CT (a, b, c) shows the pronounced thickening of the bowel wall in the ascending colon (indicated by the arrow).

Figure 2. Colonoscopy image at diagnosis.

Colonoscopy illustrating edematous folds and mild stenosis of the ascending (a, b) and sigmoid colon (c).

Figure 3. Upper endoscopy image at diagnosis.

Upper endoscopy reveals discolored and depressed lesions in the anterior wall of the fornix (a) and the angulus (b) (indicated by the arrow). Magnifying blue laser imaging reveals an irregular surface pattern with irregular microvasculature in the depressed area of the angulus (c).

Figure 4. Histological examinations of the ascending colon specimen.

Hematoxylin and eosin staining demonstrates the presence of poorly differentiated adenocarcinoma with signet ring cell within the mucosal tissue (a). Immunohistochemistry results reveal positive staining for cytokeratin 7 (b), estrogen receptor (c), and gross cystic disease fluid protein 15 (d), while showing negative staining for cytokeratin 20 (e) and E-cadherin (f).

Figure 5. Abdominal CT images after anastrozole and palbociclib therapy.

A metastatic lesion in the ascending colon (indicated by the arrow) shows no obvious tumor enlargement (a, b, c).

Figure 6. Colonoscopy image after anastrozole and palbociclib therapy.

Colonoscopy shows a reduction of edematous folds and the disappearance of intestinal stenosis of the ascending (a) and sigmoid colon (b).

Figure 7. Upper endoscopy after anastrozole and palbociclib therapy.

Upper endoscopy reveals a reduction and indistinctness of the metastatic lesion in angulus (a, b) (indicated by the arrow). Magnifying blue laser imaging shows a shrinkage of an irregular surface pattern with irregular microvasculature in the tumor lesion (c).