Breast cancer occurs when normal breast cells mutate and gain the ability to proliferate uncontrollably, forming a tumor. Breast cancer cases are staged and characterized according to the cell type they originated from, the invasiveness of the cancer and other characteristics of the tumor. Low-grade breast cancers are not highly invasive, and the tumor is localized within the breast and possibly the lymph nodes. There are a number of different low-grade breast cancers.
Low-Grade Ductal Carcinoma
Low-grade ductal carcinoma--also called ductal carcinoma in situ or DCIS--develops from mutation of cells within the ducts of the breast, the tubes that carry milk from the milk-producing lobules to the nipple. DCIS is a low-grade cancer because it is not yet invasive, but left untreated it may progress into a dangerous and invasive carcinoma.
BreastCancer.org reports that DCIS is rarely detected in a physical examination because the tumor is typically fairly small. In some cases, it may present as a lump or cause abnormal nipple discharge. DCIS is most commonly detected on a mammogram. Because DCIS is a low-grade tumor, it can often be treated with breast-conserving surgery to remove the tumor while leaving neighboring breast tissue intact.
Low-Grade Lobular Carcinoma
Low-grade lobular carcinomas are a low-grade breast cancer that affect the lobules of the breast. It's also called lobular carcinoma in situ, or LCIS. The lobules are structures that produce and secrete milk proteins and fats, and mutation to the lobule cells may cause LCIS. LCIS is classified as a Stage 0 or earliest-stage breast cancer, according to Imaginis. Women with LCIS have a higher chance of developing invasive breast cancer. Imaginis reports that LCIS can be treated with hormonal therapy, such as Tamoxifen, or by preventative breast removal surgery.
Low-Grade Spindle-Cell Carcinoma of the Breast
Although DCIS and LCIS account for the vast majority of low-grade breast cancer cases, some patients may develop a low-grade cancer called spindle-cell carcinoma of the breast. Spindle cell carcinoma of the breast is a variant of another type of cancer, metaplastic carcinoma, which can affect a number of organs throughout the body. A study published in the American Journal of Surgical Pathology in 2001 characterized spindle-cell carcinoma of the breast as a non-invasive, low-grade tumor. The study reports that treatment for this rare form of tumor involves either breast-conserving surgery or mastectomy to remove the affected breast. In very rare cases, spindle-cell carcinoma of the breast can develop into an invasive and metastatic cancer.
