DCIS vs Invasive Breast Cancer: Key Differences

DCIS vs invasive breast cancer: at a glance

How DCIS and invasive breast cancer compare, using NHS, NICE and WHO information.
Feature	DCIS	Invasive breast cancer
Where the cells are NHS inform (Scotland): Breast cancer in women	Non-invasive (in situ): still inside the milk ducts	Spread outside the milk ducts or lobules into nearby breast tissue
How early it is NHS inform (Scotland): Breast cancer in women	The earliest possible form of breast cancer	What people usually mean when they say “breast cancer”
How it is usually found NHS inform (Scotland): Breast cancer in women	Usually found during routine breast screening	A breast lump is the most common symptom; screening can also find it
Can it spread? World Health Organization: Breast cancer fact sheet	The in situ form is not life-threatening	Can spread to lymph nodes or other organs, which can be life-threatening
Armpit (lymph node) surgery NICE NG101: Surgery to the breast and axilla	Not routine with breast-conserving surgery unless invasion is likely; offered with a mastectomy	Sentinel lymph node biopsy, or node clearance if spread to the nodes is proven
Radiotherapy after breast-conserving surgery NICE NG101: Radiotherapy after breast-conserving surgery	Considered, after talking through the benefits and risks	Whole-breast radiotherapy offered when margins are clear; partial-breast for some at low risk
Medicines after surgery NICE NG101: Early and locally advanced breast cancer	Hormone (endocrine) therapy discussed if the DCIS is ER-positive	Chemotherapy, hormone or targeted therapy considered by the specialist team
Follow-up NICE NG101: Follow-up imaging	A mammogram every year for 5 years	A mammogram every year for 5 years

Each row links to the NHS, NICE or WHO page it comes from. On a small screen, scroll the table sideways.

Key takeaways

DCIS is non-invasive: the cells have not spread outside the milk ducts. Invasive breast cancer has spread into the surrounding breast tissue. (NHS inform (Scotland): Breast cancer in women)
DCIS is the earliest possible form of breast cancer and is usually found during routine breast screening. (NHS inform (Scotland): Breast cancer in women)
If DCIS is left untreated, the cells may eventually be able to spread into nearby tissue and become an invasive cancer. (University Hospitals Coventry and Warwickshire NHS Trust: Wide local excision (for DCIS) leaflet)
NICE recommends a mammogram every year for 5 years after treatment for breast cancer, including DCIS. (NICE NG101: Follow-up imaging)
A team of specialists, including a clinical nurse specialist, helps each person through diagnosis and treatment and can answer questions. (NHS: Tests and next steps for breast cancer in women)

What does “in situ” mean in DCIS?

DCIS stands for ductal carcinoma in situ. “In situ” means the cancer cells are inside the milk ducts and have not spread within or outside the breast.

An NHS hospital leaflet describes DCIS as an early form of breast cancer that is often called pre-cancerous or non-invasive. NHS inform calls it the earliest possible form of breast cancer and says it is usually found during routine breast screening.

Sources: University Hospitals Coventry and Warwickshire NHS Trust: Wide local excision (for DCIS) leaflet; NHS inform (Scotland): Breast cancer in women

What makes breast cancer invasive?

Invasive breast cancer is when cancer cells have spread outside the milk ducts or lobules where they started, into the surrounding breast tissue. When people talk about breast cancer, they usually mean invasive breast cancer.

The WHO explains that invasive cancers can spread to nearby lymph nodes or other organs, and that breast cancers are more likely to be treated successfully when they are small and have not spread to the lymph nodes.

NICE says the oestrogen receptor (ER), progesterone receptor (PR) and HER2 status of every invasive breast cancer should be checked at diagnosis, so the results are ready when the team plans treatment.

Sources: NHS inform (Scotland): Breast cancer in women; World Health Organization: Breast cancer fact sheet; NICE NG101: Assessment of tumour profile and genetic testing

Why is DCIS treated if it has not spread?

If DCIS is left untreated, the cells may eventually develop the ability to spread from the ducts into the surrounding tissue and become an invasive cancer.

The NHS also explains a wider point about screening: doctors cannot always tell whether a cancer will go on to be life-threatening, so treatment is always offered when breast cancer is diagnosed. This means some cancers that are treated would never have been life-threatening, and the NHS calls this the main risk of breast screening.

The NHS lists ductal carcinoma in situ among the breast conditions that can make breast cancer more likely in future.

Sources: University Hospitals Coventry and Warwickshire NHS Trust: Wide local excision (for DCIS) leaflet; NHS: Why breast screening is done; NHS: Causes of breast cancer in women

How does treatment differ for DCIS and invasive breast cancer?

Surgery is usually the main treatment for breast cancer, and it is used for DCIS too. A wide local excision removes the area that contains cancer or DCIS with a margin of normal tissue, and a mastectomy removes the whole breast. For DCIS, the type of surgery depends on things like the position and size of the DCIS and the size of the breast.

Lymph nodes: NICE says sentinel lymph node biopsy is not routine for DCIS treated with breast-conserving surgery unless invasive cancer is likely, but it is offered to everyone having a mastectomy for DCIS.
Radiotherapy: after breast-conserving surgery, NICE says it should be offered for invasive cancer with clear margins and considered for DCIS after a shared discussion.
Medicines: NICE says chemotherapy, hormone or targeted treatment should be considered for invasive breast cancer, and that hormone therapy should be discussed for ER-positive DCIS.

Sources: NHS: Treatment for breast cancer in women; University Hospitals Birmingham NHS Foundation Trust: Wide local excision of a breast lump leaflet; University Hospitals Coventry and Warwickshire NHS Trust: Wide local excision (for DCIS) leaflet; NICE NG101: Early and locally advanced breast cancer

Frequently asked questions

Is DCIS cancer?

DCIS is an early form of breast cancer. It is non-invasive, which means the cancer cells are inside the milk ducts and have not spread within or outside the breast. It is sometimes described as pre-cancerous. If it is left untreated, the cells may eventually be able to spread and become an invasive cancer.

Source: University Hospitals Coventry and Warwickshire NHS Trust: Wide local excision (for DCIS) leaflet

Can DCIS turn into invasive breast cancer?

It can. An NHS hospital leaflet explains that if DCIS is left untreated, the cells may eventually develop the ability to spread from the ducts into the surrounding tissue and become an invasive cancer. This is why the treatment options are discussed with each person after DCIS is diagnosed.

Source: University Hospitals Coventry and Warwickshire NHS Trust: Wide local excision (for DCIS) leaflet

How is DCIS usually found?

NHS inform says DCIS is usually found during routine breast screening. Breast screening is a way of finding breast cancer at an early stage, when it is too small to be felt or seen. Anyone who notices a symptom or anything unusual in their breasts should speak to a GP or doctor.

Source: NHS inform (Scotland): Breast cancer in women

Is radiotherapy used for DCIS?

Sometimes. NICE says radiotherapy should be considered for DCIS after breast-conserving surgery with clear margins, with the possible benefits and risks talked through so a shared decision can be made. For invasive breast cancer treated with breast-conserving surgery and clear margins, NICE says whole-breast radiotherapy should be offered.

Source: NICE NG101: Radiotherapy after breast-conserving surgery

What follow-up is there after DCIS?

NICE recommends a mammogram every year for 5 years for everyone who has had or is being treated for breast cancer, including DCIS. For women, yearly mammograms carry on after 5 years until they join the NHS Breast Screening Programme. NICE says ultrasound and MRI are not routinely used for this follow-up.

Source: NICE NG101: Follow-up imaging

Does having DCIS raise the chance of breast cancer later?

The NHS lists ductal carcinoma in situ among the breast conditions that can make someone more likely to get breast cancer. Anyone with questions about their own risk can ask their breast care team or a GP, who can explain what it means for them.

Source: NHS: Causes of breast cancer in women

Sources and references

This page is general information, not medical advice. A GP or doctor can advise on your own situation. Source links do not imply endorsement by the NHS or another organisation. See our editorial policy.

DCIS vs invasive breast cancer