Breast cancer is the second most common cancer to metastasize to the GI tract, following malignant melanoma. Although GI metastasis from invasive breast cancer is rare (< 1% in clinical practice), the incidence might be underestimated and is likely to increase [7, 8]. Autopsy series report a rate of GI tract metastasis up to 15% [8]. With early diagnosis and as treatment regimens improve, survival rates of breast cancer are increasing. With an ageing population and an increasing number of cancer survivors we might expect to encounter more unusual presentations with distant metastasis in the near future [9, 10, 12].
ILC has a metastatic rate of 4.5% to the GI tract, invasive ductal carcinoma only 0.2% [8]. GI metastasis is usually associated with extensive systemic spread [8]. Sites of metastasis can vary from the oropharynx to the anus. Anorectal involvement is very rare [13, 14]. Rectal metastasis from ILC usually occurs 5–7 years after diagnosis of the primary tumor, but there have been cases reported with synchronously rectal metastasis, as well as metastasis up to 20–30 years after diagnosis of primary ILC [5, 15].
A thorough review of literature was performed in PubMed, Embase and Web of Science. We used the following search terms: ‘Breast Cancer’ in combination with ‘Anal Metastasis’, ‘Anorectal’ and ‘Anal Canal’. This search method revealed only six individual cases of anal involvement so far, three with a history of invasive lobular carcinoma and three with a history of invasive ductal carcinoma (Table 1) [7,8,9,10,11,12].
The combination of its rarity, the often unusually long interval and the non-specific clinical presentation makes the diagnosis of GI metastasis from primary breast carcinoma a challenge. Early recognition and correct diagnosis is important for an adequate therapeutic strategy [9, 14].
GI metastatic disease should always be considered when a patient with a history of BC presents with abdominal complaints, even many years after the diagnosis of BC. Symptoms depend on the localization of metastatic disease, such as diarrhea, constipation, obstruction, incontinence, weight loss, tenesmus. Most symptoms are non-specific and may be considered treatment-related or as inflammatory GI disease. They can also mimic a primary cancer of the GI tract, which is more common than isolated GI metastasis of primary BC [2, 5].
Imaging studies may be helpful for diagnosis, but radiological features may mimic primary neoplasms or inflammatory changes, as was the case for this patient.
Endoscopy is important in making a correct diagnosis [8, 14]. The metastatic lesion may simulate inflammatory bowel disease macroscopically, so taking biopsies is important. The most common manifestation of anorectal involvement is diffuse infiltration, leading to thickening and rigidity of the rectal wall and narrowing of the lumen. As is the case for our patient, most rectal lesions appear more linitis plastica-like, rather than a solitary intraluminal mass [15]. Although endoscopy with biopsy remains the best diagnostic method, it can give false negative results, for example when the tumor is submucosal. Biopsies of the thickened stomach wall of our patient could not confirm metastatic disease, although it was a suspect lesion macroscopically. Repeated biopsies may be necessary [13,14,15].
Histopathological diagnosis of metastatic lesions can be challenging as well. The lack of dysplasia of the rectal mucosa is often helpful in distinguishing between a primary and metastatic lesion. Immunohistochemical techniques will allow for the most accurate diagnosis. ER, PR and HER2-neu status should be compared with the features of the primary breast tumor [4, 16].
Data on treatment for patients with BC and GI metastasis are rare. Many patients are treated with chemotherapy, hormonal therapy or a combination of both. Radiotherapy was strongly recommended by Puglisi et al. in elderly with anal involvement. Surgery should be limited to cases with complications such as stenosis or obstruction, or for obtaining a diagnosis [2, 4, 10, 11, 14].
Although survival of patients with BC and GI metastasis is increasing, prognosis is still poor. GI tract metastasis is often associated with extensive disseminated disease. Our patient had progressive bone metastases, peritoneal involvement was seen during laparoscopy and later on a suspect gastric lesion was found. Average survival after diagnosis of GI metastases is 1–2 years [6, 10, 14].
This case report highlights the importance of a high index of clinical suspicion for metastatic disease in a patient with a previous history of breast malignancy, ILC in particular, presenting with new GI symptoms. Clinical, endoscopic and radiological features may be variable, non-specific and misleading. This makes a correct diagnosis difficult and probably causes an underestimation of this pathology. Recognizing that GI metastasis may occur many years after the primary diagnosis of BC is important and demonstrates the need for long-term follow-up. Early and accurate diagnosis is essential for subsequent appropriate treatment. As GI tract involvement is mostly seen with extensive metastatic disease, prognosis is still poor.
