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DCIS is abnormal cells confined to the milk ducts of the breast; it is not yet invasive cancer and cannot spread, but some would become invasive if left. Lumpectomy with radiotherapy, or mastectomy, halves local recurrence, so the live question is which low-risk DCIS can safely be watched: the COMET trial (2024) found active monitoring no worse at two years.
Ductal carcinoma in situ is a non-obligate precursor of invasive breast cancer: neoplastic epithelial cells fill the ducts without breaching the basement membrane. It is almost always detected as microcalcifications on screening mammography, is graded low, intermediate or high by nuclear grade and necrosis, and is characterised by ER, PR and HER2 status. Natural-history data from misdiagnosed or untreated cases and from autopsy series show that a substantial share of low-grade DCIS never progresses, which makes overdiagnosis and overtreatment the central problem of the disease.
Standard treatment is breast-conserving surgery with clear margins (2 mm) followed by whole-breast radiotherapy, which halves local recurrence (about half of recurrences being invasive) without affecting survival, or mastectomy for extensive disease; sentinel node biopsy is done only with mastectomy or suspicion of invasion. Adjuvant endocrine therapy (tamoxifen, or an aromatase inhibitor in postmenopausal women per NSABP B-35 and IBIS-II DCIS) reduces ipsilateral and contralateral events in ER-positive DCIS. Genomic assays (Oncotype DX DCIS Score, DCISionRT) and clinicopathological tools help identify women who can omit radiotherapy. Three randomised trials test active monitoring against surgery for low-risk DCIS: COMET (US; JAMA, December 2024) reported that active monitoring was non-inferior for the two-year rate of ipsilateral invasive cancer, LORIS (UK) and LORD (Netherlands, now including a patient-preference cohort) continue to follow patients. Longer follow-up is needed before monitoring becomes routine, but the results have already changed how DCIS is discussed with patients.
The frontier is a risk-stratified approach in which high-grade or HER2-positive DCIS is treated fully while low-risk lesions are watched, informed by molecular classifiers and, potentially, by preventive vaccines against HER2 or other DCIS antigens.
About one in five to one in four breast cancers detected by mammographic screening is DCIS; it was rare before screening and is now diagnosed in tens of thousands of women a year in the US alone (SEER; NCI).
Most cancers start in the ducts and drain first to the axillary nodes, which is why the armpit is checked and a sentinel node is sampled.
Same organ: Triple-negative breast cancer (TNBC), Breast cancer (all types), HR-positive / HER2-negative breast cancer, HER2-positive breast cancer, Male breast cancer, High-risk early HR-positive breast cancer, HR-positive metastatic breast cancer after CDK4/6 inhibitors, HER2-low and HER2-ultralow metastatic breast cancer, Early HER2-positive breast cancer, HER2-positive breast cancer with brain metastases, Early triple-negative breast cancer, Metastatic triple-negative breast cancer, Basal-like 1 triple-negative breast cancer (BL1), Basal-like 2 triple-negative breast cancer (BL2), Mesenchymal triple-negative breast cancer (M), Mesenchymal stem-like triple-negative breast cancer (MSL), Luminal androgen receptor triple-negative breast cancer (LAR), Immunomodulatory triple-negative breast cancer (IM), Metaplastic breast carcinoma, Carcinoma with medullary pattern (medullary breast cancer), Adenoid cystic carcinoma of the breast, Apocrine carcinoma of the breast, Secretory carcinoma of the breast, BRCA-associated triple-negative breast cancer, Inflammatory breast cancer, Paget disease of the nipple, Phyllodes tumour of the breast, Invasive lobular carcinoma of the breast, Invasive breast carcinoma of no special type (invasive ductal carcinoma), Tubular carcinoma of the breast, Mucinous carcinoma of the breast, Papillary carcinomas of the breast (encapsulated, solid and invasive papillary), Invasive cribriform carcinoma of the breast, Invasive micropapillary carcinoma of the breast, Neuroendocrine neoplasms of the breast, Lobular carcinoma in situ (LCIS)
Nothing recorded yet.
Nothing recorded yet.
Also on OnCo: Symptoms and red flags · Early detection roadmap.
Lumpectomy to 2 mm margins followed by whole-breast radiotherapy (hypofractionated), with radiotherapy omission considered for low-risk lesions (RTOG 9804 criteria or genomic assay).
Mastectomy with sentinel node biopsy and optional reconstruction; radiotherapy not needed after mastectomy with clear margins.
Tamoxifen (or anastrozole in postmenopausal women) for five years to reduce ipsilateral and contralateral breast events; low-dose tamoxifen is an option (TAM-01).
Active monitoring with mammography every six months and optional endocrine therapy, in trials (COMET, LORIS, LORD) or after shared decision-making where guidelines allow.
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Query for this cancer: (TITLE:"Ductal carcinoma in situ" OR ABSTRACT:"Ductal carcinoma in situ" OR TITLE:"DCIS" OR ABSTRACT:"DCIS" OR TITLE:"Stage 0 breast cancer" OR ABSTRACT:"Stage 0 breast cancer" OR TITLE:"Pre-invasive breast cancer" OR ABSTRACT:"Pre-invasive breast cancer" OR TITLE:"Intraductal carcinoma" OR ABSTRACT:"Intraductal carcinoma" OR TITLE:"stage 0 breast cancer" OR ABSTRACT:"stage 0 breast cancer") AND (treatment OR therapy OR trial OR survival OR diagnosis). Results are unfiltered search hits about Ductal carcinoma in situ (DCIS), not a curated reading list.
The concept of non-invasive cancer confined by the basement membrane.
Incidence rises several-fold in screened populations.
Halves local recurrence; no survival difference.
Aromatase inhibitor an alternative in postmenopausal women.
Hwang and colleagues (JAMA, December 2024); first randomised evidence for monitoring low-risk DCIS.
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Breast Cancer Now lists headache, sickness and vomiting especially on waking, weakness or numbness down one side of the body, unsteadiness or loss of balance, seizures, difficulty with speech, vision problems, and changes in behaviour, mood or memory among the signs that breast cancer may have spread to the brain. A seizure, a sudden severe headache or new one-sided weakness is 999 whatever the cause.
The NHS says to call 999 or go to A and E if you have cellulitis with a very high temperature or you feel hot, cold or shivery, a fast heartbeat or fast breathing, purple patches on the skin which may be less obvious on brown or black skin, feeling dizzy or faint, confusion or disorientation, cold, clammy or pale skin, or unresponsiveness. These are symptoms of serious complications, which can be life threatening.
Breathing very fast; confused, slurred speech or not making sense; blue, pale or blotchy skin, lips or tongue; a very high or very low temperature, feeling hot or cold to the touch, or shivery; a rash that does not fade when pressed: the NHS says call 999 or go to A and E, and do not drive yourself, ask someone to drive you or call 999.
NICE NG234 says to immediately contact the metastatic spinal cord compression coordinator if a person with a past or current diagnosis of cancer presents with bladder or bowel dysfunction, gait disturbance or difficulty walking, limb weakness, neurological signs of spinal cord or cauda equina compression, numbness, paraesthesia or sensory loss, or radicular pain, and to treat this as an oncological emergency. If you cannot reach anyone, go to A and E and say you have breast cancer and symptoms of spinal cord compression.
A swollen painful calf, or sudden breathlessness with chest pain; the tamoxifen boxed warning covers pulmonary embolism and stroke.
Possible QT prolongation. Check ECG and electrolytes; review other QT-prolonging drugs.
See all on the product pages:Bone metastases and skeletal-related eventsBrain metastases (intracranial disease)Compression, decongestive therapy and exercise for lymphoedemaFebrile neutropeniaLymphadenectomy (lymph node dissection)Lymphoedema after breast cancer treatmentMetastatic spinal cord compression (MSCC)Neutropenic sepsis: the temperature rule and the 999 signsSeroma after breast surgerySurvivorship care and late-effects surveillanceTamoxifen·Printable cards in the navigator
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