What Is Ductal Carcinoma In Situ?

Breast Cancer is one of the world’s most commonly diagnosed cancers, with 2.3 million new cases diagnosed in 2020 alone. A diagnosis of any form of cancer can leave a patient with many questions, including more of an explanation of the type of cancer they have. Breast Cancer can be divided into two groups: invasive and non-invasive. Ductal carcinoma in situ (DCIS) is a type of non-invasive breast cancer, which means it has not spread from its original location into surrounding breast tissue.¹ DCIS is a very early-stage diagnosis that could progress into a more dangerous invasive form. To find out more about DCIS, click on the link below. 

Overview

To better understand what DCIS is we can split up the name into 3 parts: “Ductal”, “Carcinoma and “In Situ.” 

• Ductal refers to the location of the cancer within the milk ducts of the breast. 
• Carcinoma is a subtype of cancer where cancer cells develop from epithelial cells; these are the type of cells that line the ducts. 
• In situ is a term used in cancer staging and can be considered as stage zero. This is where the cancer is small, and the abnormal cells have not invaded the surrounding breast tissue. 

The term “pre-invasive lesion” can be used to describe DCIS because the cancer cells have not yet progressed into invasive breast cancer. Ductal Carcinoma in Situ can further be subdivided into 5 separate groups to determine how the DCIS may behave in the future and their likelihood of becoming invasive breast cancer. These groups are: ²

• Comedo DCIS – which has the highest chance of becoming an invasive breast cancer
• Micopapillary DCIS
• Papillary DCIS
• Cribriform DCIS
• Solid DCIS

DCIS makes up 20% of new breast cancer diagnoses. Invasive ductal cancer is by far the most common subgroup, with 70% of invasive breast cancers being of ductal carcinoma type.1,3 Invasive breast cancer is where the cancer cells begin to spread or “invade” into the surrounding breast tissue and extend outside of the breast ducts. As a result, DCIS is a very serious diagnosis that requires prompt treatment. Without treatment, the cancer progresses to become invasive within 2 years.1 Progression to invasive ductal carcinoma can lead to metastatic breast cancer, where the cancer spreads beyond the breast to other parts of the body, including your lymph nodes.

Causes of ductal carcinoma in situ 

Generally, cancers are caused by the malignant transformation of normal cells in your body. Your body is constantly multiplying, making new cells and this needs to happen perfectly every single time. Unfortunately, this process (mitosis) does not always go according to plan. This can lead to mutations within the DNA of your cells. Cancers occur when the mutations lead to cells that grow at an abnormal rate. Normally, your body has a range of different processes to identify cells that have gone wrong, immediately terminating them. These processes involve a complex network of interactions between your immune system and proteins your body produces to prevent these cells from multiplying, which is known as tumour suppressors. Reasons why this process can go awry can be the result of a combination of genetic factors and environmental factors. These factors can provide the perfect environment for these normal cells to become abnormal, or they may initiate damage to your DNA, which causes them to become cancer cells. Environmental factors that increase the risk of developing breast cancer include: ⁴

• Increasing age 
• Use of hormone replacement therapy in postmenopausal individuals who are assigned female at birth (AFAB) and use of hormonal contraceptives
• Being overweight 
• Alcoholism
• First pregnancy after the age of 30
• A history of radiation therapy treatment

There is a particularly strong genetic component for the development of breast cancer. Having either BRCA1 or BRCA2 genes or both increases the risk of developing breast cancer drastically as an AFAB, with a 70% risk of breast cancer before the age of 80. Only 1 in 400 AFABs carry one of these mutations. However, a family history of breast cancer is something you should consult your doctor with.⁴ 

Signs and symptoms of ductal carcinoma in situ

The majority of the time, ductal carcinoma in situ is diagnosed during breast cancer screening as it does not typically have any symptoms. However, symptoms that could indicate DCIS include: ¹

• A lump in the breast
• A discharging nipple 

Management and treatment for ductal carcinoma in situ

The treatment of DCIS is through surgery with two options: breast-conserving surgery or mastectomy.

Breast-conserving surgery is where the surgeon removes the area with cancer and a small portion of breast tissue, conserving the rest of the breast. This is typically the option for those who have early-stage breast cancer like DCIS. This may be followed up with radiotherapy, which is to ensure all the cancer cells have been removed and to prevent the recurrence of DCIS. 

The other option is mastectomy, where the surgeon removes the entire breast. This option is only reserved where there are multiple DCIS lesions throughout the breast or if the lesion is quite large. After having a mastectomy, you would then have what is known as a sentinel lymph node biopsy. A sentinel lymph node is the first lymph node where the cancer cells are most likely to spread and this lymph node is removed to be examined for any cancer cells within it. After a mastectomy, you may be offered breast reconstruction.

FAQs

How is ductal carcinoma in situ diagnosed?

Ductal carcinoma in situ is diagnosed through breast screening. AFABs aged 50-71 in the UK are at risk of developing breast cancer and are advised to get a mammogram. This is a special X-ray of the breast to identify any abnormalities in the breast tissue. A biopsy of the affected breast tissue may be required and sent off for histology, where the tissue will be viewed under a microscope, and the diagnosis is given.

Can I prevent ductal carcinoma in situ?

There are some things that can be done to prevent DCIS. They are:⁵

• Remaining active 
• Maintaining a healthy weight 
• Cutting out smoking and alcohol consumption
• Schedule regular breast exams with your GP 

Generally, you can prevent breast cancer by living a relatively healthy lifestyle.

How common is ductal carcinoma in situ?

DCIS makes up under a quarter of all new breast cancer diagnoses, and breast cancer is the most commonly diagnosed cancer as of 2020, with 2.3 million new cases worldwide.¹

Who is at risk of ductal carcinoma in situ?

The people who are at risk of DCIS are: ⁴

• Those who are overweight
• Those who consume alcohol excessively
• Those who smoke regularly
• Those with a family history of breast cancer, particularly if any AFABs in the family have been diagnosed
• Those with a previous history of any other type of cancer, especially if they received radiation treatment around the chest

When should I see a doctor?

While DCIS is commonly diagnosed on breast cancer screening appointments, it is still a good idea to look for general symptoms of breast cancer. See your doctor if you have:

• A lump in the breast 
• A discharging nipple 
• Dimpling in the breast
• Sudden reddening on the nipple

Summary

Ductal carcinoma in situ is a pre-invasive breast cancer that is normally found during breast screenings. Those with DCIS do not normally experience any symptoms. It is an early stage of breast cancer and needs prompt treatment to prevent it progressing into invasive breast cancer. Scheduling regular breast exams with your healthcare provider can improve your chance of curing DCIS by catching it early.