Invasive Ductal Carcinoma 

Invasive Ductal Carcinoma (or IDC) is the most common type to affect breast cancer patients. IDC is a cancer that begins in the cells lining the inside of milk ducts in the breasts but has broken through the walls of these ducts and began to spread into the surrounding breast tissue or further to distant organs.

Invasive ductal carcinoma means that the cancer has spread or ‘invaded’ from its original location to the surrounding breast tissue. Ductal refers to the presence of cancer cells within the milk ducts of the breast. Carcinoma is a term used to describe cancer cells that first appear in the skin or the tissue lining internal organs.  

IDC is different from Ductal Carcinoma in Situ (DCIS), a type of pre-invasive breast cancer. DCIS is considered the earliest stage of breast cancer and will not have spread any further than the milk ducts inside the breast. Because of this, it is known as non-invasive breast cancer. IDC, on the other hand, has moved into surrounding tissue or further to distant organs.

IDC can be diagnosed anywhere from early breast cancer to late-stage/advanced cancer and will be categorised by your doctor from stages 1 to 4 (stage 0 is used to classify breast cancers that are pre-invasive and have not spread, such as DCIS and lobular carcinoma in situ or LCIS). This classification is made based on the size of the cancer, whether or not it has spread to draining lymph nodes, and whereabouts in the body cancer cells have been found.

Overall, breast cancer in women has a 5-year survival rate of 92% at diagnosis. The survival rate of breast cancer is highly dependent on the stage at diagnosis, with 100% of those diagnosed with Stage 1 surviving 5 years after their diagnosis, whereas the five-year survival rate for Stage 2 breast cancer is at 94.6%, for Stage 3 80.2% and for Stage 4 (metastatic breast cancer) 32%.  

Whilst breast cancer can happen to anyone, there are several risk factors which can increase the likelihood of being diagnosed. These include:  

• Age: 80% of breast cancers are diagnosed in women aged 50 or over
• Family History: Whilst most breast cancers, including invasive ductal carcinoma, are not hereditary, for a small number of women there may be a gene change in a blood relative which can increase the chance of breast cancer. It is thought that about 5-10% of breast cancers are hereditary.
• Previous benign breast disease: This is the term given to non-cancerous breast conditions where the cells grow abnormally.

Symptoms of Invasive Ductal Carcinoma 

While there are some signs and symptoms of IDC to look out for, it’s important to remember that, like with any breast cancer, some women – particularly those in the early stages – may not notice any symptoms at all. The cancer may be first discovered on a routine mammogram before any symptoms are noticed, making regular check-ups all the more essential. However, there are some potential signs of IDC to look out for, including:  

• changes in the breast shape 
• breast or nipple pain 
• discharge from the nipple 
• swelling of the breast 
• a lump 
• thickening of the nipple skin

If you notice any unusual changes in your breasts, it’s important to see a doctor as soon as you can.  

Diagnosis for Invasive Ductal Carcinoma 

Invasive ductal carcinoma can be diagnosed using a combination of medical tests. This may include taking a personal history and a clinical breast examination, a mammogram and/or ultrasound and a biopsy.

Stages of Invasive Ductal Carcinoma 

As with other types of cancer, IDC can be classified by the stage at which it is diagnosed. This allows doctors to categorise how far the cancer has spread beyond the original location of the milk duct and can be useful for diagnosing further treatment. The stage of the cancer depends on the size of the tumour, whether the lymph nodes are involved and how far it has spread beyond the breasts and lymph nodes. Stages of invasive ductal carcinoma are numbered from 1 to 4.

Stage 1 and 2 refer to ‘early breast cancer’. This means although the cancer is invasive, it is still contained in the breast. It may or may not have spread to the lymph nodes in the armpit  (Stage 2 only) or remain confined to the breast (Stage 1). The 5-year survival rate for stage 1 breast cancer is, on average, 100%, and for stage 2, 94.6%.

Stage 3 refers to locally advanced breast cancer, including IDC. It is more advanced than stage 2 cancer, having potentially been found in several lymph nodes and tissues near the breast (though it hasn’t been detected elsewhere in the body). The 5-year average survival rate for stage 3 breast cancer is 80.2%. 

Stage 4 is also known as advanced or metastatic breast cancer, meaning it has spread to other parts of the body beyond the breast, such as the bones, brain and/or other organs. The 5-year survival rate for stage 4 cancer is 32%.

Treatment for Invasive Ductal Carcinoma 

There are several different options which may be recommended to treat IDC. A decision on what treatments are recommended for any individual are made by the treating team (a multidisciplinary team consisting of surgeons, medical oncologists, radiation oncologists, pathologists, radiology, supportive care and general practice). Below are some of these options:  

Surgeries 

Surgery is often recommended as the first stage in the treatment for the earlier stages of IDC but is not usually recommended for women with metastatic IDC. Depending on the stage of the tumour at diagnosis (size and spread of the tumour), surgery can take the form of either breast conserving surgery (lumpectomy, complete local excision, partial mastectomy or wide local excision) – where the breast cancer is removed and a small amount of healthy breast tissue or alternatively a mastectomy, which is the removal of the entire breast. During both types of surgeries, some women will also have one or more lymph nodes from the armpit (axilla) removed.  

Radiation therapy 

Radiation therapy involves the delivery of high energy and ionising radiation to the affected area in the breast. Some women may also have radiotherapy on their underarm area. Radiotherapy is almost always recommended after breast conserving surgery such as a lumpectomy, to target any remaining cancer cells. Radiotherapy is sometimes recommended after a mastectomy. Radiotherapy may also be used for women with metastatic breast cancer to manage pain, relieve symptoms, prevent fractures and treat the cancer that has spread to other parts of the body (eg bones, brain and lymph nodes).

Chemotherapy 

Chemotherapy involves taking anti-cancer medicine, either in the form of pills or through an IV drip. Chemotherapy may be recommended for women with any stage of IDC, to either prevent the cancer from returning (early IDC and if there is a risk that the cancer has spread beyond the breast including the underarm area) or stop the cancer from growing and spreading (metastatic breast cancer). The decision to recommend chemotherapy will be based on several factors that include:  

• The type, stage and grade of the cancer 
• The risk that the cancer will recur or spread to other parts of the body 
• The hormone receptor status of the cancer (which can affect the timing and type of chemotherapy that might be recommended) 
• The age and health of the patient  
• The patient’s preference

Hormone therapy 

Hormone therapy may be recommended for patients with early or metastatic breast cancer whose breast cancer tests positive for hormone receptors. These are special proteins which promote the continued growth of cells in the presence of hormones such as estrogen or progesterone. Hormone therapy drugs include tamoxifen and aromatase inhibitors. 

Targeted therapy 

Like hormonal therapies, targeted therapies may be recommended for patients with early or metastatic breast cancer to target specific types of cells characterised by the presence of a ‘marker’. An example of such a marker is HER2, human epidermal growth factor receptor 2, a special protein that is present in normal breast cells. When over-expressed (present at very high levels), the breast cancer is classified as HER2 positive. HER2 positive breast cancer can be treated with antibodies that bind to HER2, such as Herceptin (traztuzumab, lapatinib, Kadcyla). Other targeted therapies include Afinitor (targeting the mTOR protein), Avastin (targeting blood vessel formation), Palbociclib (targeting cancer growth via CDK4/6), Olaparib (targeting DNA damage via PARP). 

Chemotherapy for IDC will usually begin after breast surgery but in some cases, it could be before surgery to shrink the tumour(s) and destroy any rapidly dividing cancer cells. This helps the surgeon ensure that the entire tumour is removed during surgery. Chemotherapy can be used alone or in combination with hormonal or targeted therapy independently of surgery for metastatic IDC. 

If you have been diagnosed with IDC, your doctor will discuss the best course of treatment to suit your individual needs. Whilst everyone takes a different reaction to treatment, the recommendation is that the sooner treatment takes place, the better the chance of survival. 

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