Questions and answers on breast cancer
| GUIDELINE 5. DUCTAL CARCINOMA IN SITU (DCIS) |
What is DCIS?
DCIS stands for "ductal carcinoma in situ." In DCIS, the cancer is confined to the milk ducts of the breast. It is also called "noninvasive" cancer. For women who have only DCIS, the outlook is much better than for those who have invasive cancer. However, untreated DCIS may in time become invasive, spreading through the duct wall to surrounding tissue, and possibly to other parts of the body. When this happens, the cancer is no longer DCIS and must be treated as invasive cancer. The treatment described in this guideline is for women who have only DCIS.
Usually, when a woman has DCIS, there are no warning signs like a lump in the breast. Most often, DCIS shows up on a mammogram taken at a screening clinic before any symptoms appear. Because screening programs are relatively new, doctors have less experience in treating DCIS than they have in treating invasive cancers.
How common is DCIS?
With the increased use of mammographic screening programs, DCIS is being diagnosed more and more frequently in Canada. It now accounts for between 20% and 25% of all breast cancers detected in women who are screened.
How will I know for sure if I have DCIS?
First, you will go through the steps described in guideline 2, for investigation of any abnormality found by mammography. If a needle ("core") biopsy shows DCIS or if the suspicion of DCIS is very high in the first place, a surgical biopsy is essential to find out if the cancer has invaded any of the surrounding tissue. This is a crucial step, since any spread outside the milk ducts means that the cancer is no longer simply DCIS, but is now "invasive." If this is the case, the recommended treatment will be different. When a surgical biopsy is done, the abnormality is removed in one piece and x-rayed Samples of the tissue are then examined under the microscope.
If the x-ray of the removed tissue suggests that not all the cancer was removed, a second mammogram is obtained after the breast tissues have had a chance to heal. Another operation may be required to remove cancer cells left behind.
My surgical biopsy showed that I have DCIS. What is the best treatment for me?
Final treatment decisions should not be made until all of the above steps are completed and you have been fully informed about the findings. DCIS is not a fast-growing cancer, so it is quite safe to postpone your final decision for a few weeks. Take the time you need to consult with your doctors, family, friends or other women who have had breast cancer.
The first thing to consider is whether the surgical biopsy removed all the cancer. If some cancerous cells were left behind, most women choose to have the remaining diseased tissue removed by surgery. Other important factors include the type of DCIS that was found, and how much of the breast is involved.
There is some choice as to the type of surgery. In the past, a diagnosis of DCIS always meant mastectomy (removal of the whole breast), and this may still be the best option for some women. The other main option is lumpectomy (also known as breast-conserving surgery) followed by radiation treatment. Lumpectomy followed by radiotherapy is now the generally recommended treatment for early invasive breast cancer, and is also used for DCIS.
Whether you choose mastectomy or lumpectomy followed by radiotherapy, survival rates are very high: between 95% and 100% for women 10 years after surgery.
Since survival is not an issue, what other factors should I consider in choosing between mastectomy and lumpectomy?
The factors listed below should be considered. Many of them are considered in more detail in guideline 3 in this series.
- Whether the surgical biopsy succeeded in removing the whole diseased area. If microscopic examination of the removed tissue shows that there are cancerous cells at the cut edges, you may need a second or even third operation to remove more tissue. Choosing mastectomy avoids this possibility. Also, you may want to consider mastectomy if you live far from a treatment centre, since lumpectomy requires several weeks of daily radiotherapy after the surgery.
- The likelihood that the cancer will come back in the same breast. It is somewhat more likely that cancer will return if DCIS is treated by lumpectomy and radiotherapy rather than by mastectomy, but the evidence is not absolutely clear. If there are no cancer cells on the edge of the tissue which has been removed, it is estimated that cancer may come back in the first 5 years after treatment in 3% to 7% of women whose DCIS is treated by lumpectomy and radiotherapy. Mastectomy may be the better choice if your tumour is large or has other features which suggest that recurrence of the cancer is likely.
- The amount of tissue to be removed. If there is more than one tumour or if the tumour is large, a lumpectomy may require the removal of a great deal of tissue, leaving the breast disfigured. In such situations, a mastectomy followed by reconstruction of the breast is often preferable.
- The possible complications related to each procedure. All treatments carry the possibility of unwanted side effects. Persistent pain, swelling and delayed healing of the wound can occur with either lumpectomy or mastectomy, but are more common with mastectomy. However, the radiotherapy that follows lumpectomy can also cause unwanted side effects, including fatigue, pain, tenderness and scarring of the breast. For more details about radiation therapy, see guideline 6 in this series.
- Your ability to undergo radiotherapy. Radiotherapy is normally recommended after lumpectomy since it reduces the risk of the cancer coming back in the same breast. If you cannot have radiotherapy for any reason, or if it will be very difficult or inconvenient for you to do so because of your job or your distance from a treatment centre, mastectomy may be the better choice. In a small number of cases, if the tumour is quite small and has no features indicating it is especially likely to return, and if it is certain that all the diseased tissue was removed, lumpectomy may be considered without radiotherapy. However, you should not make this choice without fully exploring the issues with your doctor.
- Your personal concerns regarding appearance and feelings of well-being. Lumpectomy preserves more breast tissue than mastectomy, usually resulting in a more natural look and "feel." However, the appearance depends to a large extent on how much tissue is removed. The lower risk of recurrence after mastectomy may be more important to you than appearance. Your own feelings in this regard are important factors in making the right treatment choice.
Anxiety and depression can occur no matter which treatment you choose. Studies show that women who are fully informed about their diagnosis and treatment have these problems less often. Support from family and friends, counselling and involvement with a support group of breast cancer survivors have also proved of great value in helping women cope.
If I have a mastectomy for DCIS, can the skin and nipple be kept intact for plastic surgery later?
This procedure (called "subcutaneous mastectomy") has been done for patients with DCIS in the past because it gave a good cosmetic result. However, because it leaves 10% to 15% of the breast tissue behind, it only partly removes the risk of the cancer returning and is not as safe as mastectomy. If mastectomy is being chosen to minimize the risk that the cancer will recur, subcutaneous mastectomy is not recommended.
What about other treatments, like tamoxifen and chemotherapy?
There is no evidence that either of these treatments is of any benefit for women with DCIS.
Should the lymph nodes in the armpit also be removed?
Lymph nodes (sometimes called "glands") are frequently removed for invasive breast cancers, but not for DCIS. This is because spread to the nodes is very rare in DCIS, and any benefit of removal is outweighed by the possible complications of the operation.
