Breast cancer sub-types and the extent of surgery required

The authors aimed to evaluate whether there was a difference between the rates of local recurrence (the cancer returns to or near the site of the original tumor) in invasive lobular carcinoma and invasive ductal carcinoma.

Invasive lobular carcinoma is characterized as cancer that begins in the milk-producing lobules that then spreads to surrounding breast tissue. Invasive ductal cancer is characterized as cancer that begins in the milk-carrying ducts that then spreads to surrounding breast tissue.

These two cancer sub-types are often grouped together in many studies. There are now reports, however, that they are distinct cancer types, with invasive lobular carcinoma being the more aggressive of the two and requiring more surgical treatment. 

The aim of this study was to evaluate invasive lobular cancer in relation to the extent of surgical treatment required, as well as a mode to distinguish it from invasive ductal carcinoma.

A total of 998 women with stage 1 or 2 invasive breast cancer were evaluated. 74% of patients were diagnosed with invasive ductal carcinoma, 8% were diagnosed with invasive lobular carcinoma, and 18% had a mix of the two. All women previously underwent breast-conserving therapy (surgery that removes the breast cancer but not the breast itself).

Of the patients with invasive lobular carcinoma, 91% of these were of the luminal A sub-type. This is characterized by having hormone (estrogen and/or progesterone) receptor positive (dependent on these hormones for growth) and human epidermal growth factor receptor 2 (HER2) negative breast cancer. Only 51% of the patients with invasive ductal carcinoma were of this sub-type.

After a follow-up of 10 years, there was no significant difference in local recurrence rates between patients with invasive lobular (4.4%) and ductal (5.5%) carcinoma. There was also no significant difference in the rates of local recurrence between the patients with invasive lobular (3.4%) and ductal carcinoma (2.6%) of the luminal A sub-type.

Furthermore, patients with invasive lobular cancer did not require more extensive surgical treatment compared to their ductal counterparts.

The authors suggested that there was no significant difference in the rates of local recurrence between patients with invasive lobular or ductal carcinoma. Invasive lobular cancer did not require more surgical treatment.

This study involved a small group of patients with invasive lobular carcinoma. The study should be repeated with a larger number of patients to determine whether the results can be generalized.