Discussion
Breast cancer is the cancer with the highest incident rate in women
according to the Global Cancer Statistics in 20201.
Breast cancer often metastasizes to other organs, particularly the
lungs, bones, liver, and brain, and, very rarely, the bile duct. Thus
far, 16 cases of bile duct metastasis of breast cancer have been
reported in detail. These case reports were obtained through a search of
PubMed for articles published from 1946 to 2021, using the search terms
“breast cancer” and “biliary metastasis”. In addition to these,
Japanese case reports were obtained through a search of the Japana
Centra Revuo Medicina Web for articles published from 1977 to 2021,
using the Japanese equivalents of the search terms mentioned
above2-13. The details of these case reports are
presented in Table 1. The average age of the patients was 56 years
(42–70 years). Most cases were examined for subjective symptoms, such
as jaundice (11/16), abdominal pain (3/16), and pruritus (3/16), and
only one case was asymptomatic. The mean time to metastasis to the bile
duct was 7.4 years (2–21 years), and most of the cases further showed
metastasis to other organs such as the gallbladder, liver, and bones.
Many of the reported cases required multiple examinations for diagnosis.
In reports before the 1990s, most cases were diagnosed by histology of
resected specimens after surgery; however, recently, some cases were
diagnosed by ERCP.
Regarding treatment for objective jaundice by bile duct stenosis, only
five cases were treated by endoscopic drainage (Table
2)2,3,5,6. On cholangiography, all the reported cases
with available images showed severe diffuse stenosis confined to a
relatively long segment of the bile duct. In four of these cases, tissue
biopsy or brushing cytology at the stenotic area was performed, all of
which led to a definitive diagnosis. Conversely, Coletta et al.,
reported a case of bile duct metastasis of breast cancer, in which
endoscopic cytological examination of the stenotic area was negative;
histologic examination of the resected specimen after surgery revealed
tumor cells on the outer side of the bile duct, but not on the bile duct
endothelium7. In such cases, it is difficult to make a
definitive diagnosis based on endoscopic bile duct biopsy or brushing
cytology alone; therefore, a comprehensive approach based on clinical
history and findings on other imaging modalities are required.
Our case is the first to describe
the duration of stent patency, and in which stent stenosis due to tumor
invasion was observed repeatedly within a short
period. There was a previous case
report of gastric metastasis of breast cancer, in which an SEMS was
placed for pyloric stenosis, and obstruction due to tumor invasion was
observed barely 3 months later14. This indicates that
in the case of breast cancer metastasis, in-stent invasion may occur
earlier. Furthermore it may be useful to place SEMS in the early stages
after diagnosing biliary metastasis, as it is superior to plastic stent
from the viewpoint of stent patency. Regarding complications,
cholecystitis occurred in two of reported cases after endoscopic
stenting; however, other serious adverse complications were not
reported. Prognosis varied from case to case, depending on the degree of
progress of breast cancer and metastases.
In summary, we encountered a rare case of bile duct breast cancer
metastasis, in which obstructive jaundice was effectively managed by
endoscopic drainage. Endoscopic bile duct stenting is less invasive than
surgical operation, making it an effective treatment option.