The research goal was to compare of the metastatic pattern of invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC) at both first distant recurrence (FDR) as well as over the entire course of metastatic disease.
After accounting for hormone receptor status, patients with IDC had greater lung/pleura and liver involvement, while patients with ILC had a greater propensity to develop ovarian and GI metastases both at first site and overall. Clinicians can use this information to provide more directed screening for metastases; it also adds to the argument that these two variants of breast cancer should be managed as unique diseases.
- Mammography as a screening tool is challenged with ILC due to its infiltrative growth pattern; as a result, patients often have a delayed diagnosis.
- Because of the delayed diagnosis, ILC tumors are often larger size, better differentiated, and exhibit higher levels of estrogen receptor (ER) than IDC.
- Compared with IDC, ILC is associated with an older patient.
- ILC tumors tend to have lower Ki-67 expression than IDC
- ILC tumors tend to be HER-2 and p53 negative
Study population: 761 patients at the Magee-Womens hospital of UPMC and the University of Pittsburgh Cancer Institute who had been diagnosed with distant metastatic disease between January 1, 1998 and December 31, 2012. Of these patients, 88 (11.5%) had ILC and 673 (88.4%) had IDC.
Patients with ILC had more advanced disease at the time of primary diagnosis (31.5% stage III and 37% stage IV or de novo metastatic disease in the ILC group, compared with 23.6% stage III and 24.8% stage IV in the IDC group, p = 0.01). There was no significant difference in overall survival (time from first metastasis to death or last follow-up) between the two groups (OS was 2.0 years for IDC vs. 2.5 years for ILC, p = 0.75).
This study, with 88 patients, examines one of the largest groups of ILC patients with metastatic disease in the literature.
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