LCIS
Meaning of LCIS: Abnormal cells filling the milk-producing lobules, treated as a warning sign for both breasts rather than as a cancer of one.
Definition of LCIS
LCIS stands for lobular carcinoma in situ, a finding in which abnormal cells fill the lobules, the small milk-producing sacs of the breast. The cells stay inside the lobule and do not invade surrounding tissue. Despite carrying the word carcinoma in its name, LCIS is regarded as a marker of increased risk rather than as a cancer or a direct precursor of one.
How does it differ from DCIS?
The two share a similar name and are entirely different in meaning, which is a frequent source of confusion.
| LCIS | DCIS | |
|---|---|---|
| Where | Lobules | Ducts |
| Meaning | Marker of raised risk | Direct precursor of invasive cancer |
| Which breast is at risk | Both, roughly equally | Mainly the same site |
| Seen on mammogram | Usually not | Often, as calcium specks |
| Treated as cancer | No | Yes |
How is it found?
Almost always by accident. It forms no lump, causes no symptoms and rarely produces the calcium deposits that draw attention on a mammogram. It is usually reported when breast tissue has been sampled for some other reason, and the finding then applies to the whole breast rather than to the spot that was biopsied. This is why it is described as a marker: the abnormal cells indicate a breast in which changes are occurring, not a lesion that needs removing.
What does it mean for future risk?
Having LCIS raises the chance of developing invasive breast cancer later, and that raised chance applies to both breasts, not only the one sampled. The cancer that eventually develops may be of either the lobular or the ductal type, which is further evidence that LCIS marks a general tendency rather than seeding a specific tumor. Management centers on closer surveillance and on discussion of risk-reducing options. One variant, called pleomorphic LCIS, contains more abnormal-looking cells and is handled more like other forms of carcinoma in situ, with attention to clear margins. The naming remains awkward, and proposals to drop the word carcinoma from the classic form have been made repeatedly.
Also known as
Used in a sentence
Biopsy performed for an unrelated finding reported LCIS in the surrounding tissue.
Good to know
Classic LCIS is a risk marker rather than a cancer, and the increased risk applies to both breasts regardless of which one was sampled.