What is Invasive Breast Cancer?

As we discussed before, there are words in your biopsy report that may be difficult to understand, but there are some key phrases you can learn to help uncover the meaning of this report. Ductal carcinoma in situ and invasive breast cancer are the two most common types of breast cancer. If you would like to know more about ductal carcinoma in situ, or DCIS, read our blog “What is DCIS?” Otherwise, let’s find out more about invasive breast cancer and discover its meaning. There is a lot to cover, but I know you are ready.

When discussing invasive breast carcinoma, it is also important to understand the meaning of infiltrating ductal carcinoma. Remember, carcinoma means cancer and invasive breast carcinoma is breast cancer that has a tendency to invade others structures and tissues. While there are many different types invasive breast cancer, infiltrating ductal carcinoma is the most common. Infiltrating ductal cancer accounts for about 75 -80% of all invasive breast cancer types. (1) Normally, the cells in our body respect boundaries and do not invade other cells or tissues. The words “invasive” and “infiltrating” have similar meanings and highlight the fact that these cancer cells have “lost respect for boundaries” and therefore have a tendency to invade nearby structures. As discussed in our previous blog, ductal cells line the passageways where milk travels and tend to be a site where breast cancer develops. This is why we need to pay attention to bloody or abnormal nipple drainage, as this can be a sign of breast cancer. Therefore, infiltrating ductal carcinoma is cancer of the breast ducts that invades other tissues and structures nearby.

Another word we need to become familiar with when discussing invasive breast cancer is “differentiation.” Cancer cells arise from normal cells in our body. When cancer cells first develop, they have an appearance that is similar to the cell that they arose from. With time, cancer cells can become more aggressive and lose the appearance of the cells they originated from. This is called differentiation, or how similar a cancer cell appears when compared to the tissue of its origin. A well differentiated cancer cell has a similar appearance to the tissue that is came from. A poorly differentiated cancer cell looks completely different than the tissue it come from. Well differentiated cancer cells have a better outlook than poorly differentiated cancer cells. In other words, if the cancer cell looks just like the tissue it came from, it is less aggressive. When reading the biopsy report, find out if the cancer cells are well, moderately or poorly differentiated.

 Those with invasive breast cancer also require a unique treatment pathway that tends to involve another biopsy, surgery to remove the breast mass and radiation. Those with invasive breast cancer with require a biopsy of the sentinel node in order to determine if breast cancer has spread beyond the breast. Remember, lymph nodes as the drainage centers in our bodies and can serve as a highway for cancer to spread. The sentinel lymph node can be thought of as the first ramp to enter the highway. In order words, the sentinel node will be the first lymph node that a cancer will reach before spreading further. If the sentinel node is negative, there is likely no need to biopsy the lymph nodes under the arms, as this can lead to arm swelling over time.

For those with invasive breast cancer, surgery and radiation options may be similar to those with DCIS. Surgery can take the form or a lumpectomy or mastectomy. Remember, with lumpectomy only a portion of the breast is removed and the surgeon works to maintain the aesthetics of your breast without the need for implants. With mastectomy, the whole breast is removed and a breast implant or removable prosthetic can be considered. Radiation can involve the whole or portion of the breast.  It is important to consider that radiation can also affect the blood vessels in your heart. Therefore, pay attention to any chest pain or heart complaints in the future after receiving radiation.

In contrast to ductal carcinoma in situ, or DCIS, most women with invasive breast cancer will require chemotherapy. For invasive breast cancer, the decision for chemotherapy is complicated and based on tumor size, number of lymph nodes involved and cancer cell hormone responsive. Even more, when tumor size helps determine the need for chemotherapy, there are different size cut offs for those with ductal carcinoma in situ, or DCIS, invasive breast cancer and other breast cancer types. Also, even if no lymph nodes are involved, one may still require chemotherapy. Furthermore, if a sentinel lymph node is involved, another biopsy may be required of the lymph nodes under the arms before determining a chemotherapy plan. Similar to those with DCIS, biopsies with invasive breast cancer will also need to be tested for response to hormones.

Once a breast biopsy is obtained, there are special tests that need to be performed on this biopsy in order to determine if the cancer cells not only respond to estrogen or progesterone, but also to HER2. HER2 stands for human epidermal growth factor receptor and represents a mutation that can makes breast cancer more aggressive. This mutation is present in about 15% of all invasive breast cancers. (2) Fortunately, we can target our therapy with a medication called trastuzamab, which helps block the effects of this HER2 gene. Therefore, those with the HER2 gene would not only receive chemotherapy, but also trastuzamab.

Finally, when looking at cancer cell response to estrogen and progesterone, response to estrogen appears more important than response to progesterone. In fact, the response to progesterone only appears important if the tumor is also responsive to estrogen. Nonetheless, if the cancer cells are responsive to estrogen, then additional therapy with tamoxifen for 5-10 years can be considered. If you have reached menopause, medications such as anastrozole and letrozole may be helpful and have been shown to be more beneficial than tamoxifen. If you reach menopause while being treated with tamoxifen, your doctor may switch you to anastrozole and letrozole as well.

 Understanding your biopsy report and treatment options for invasive breast cancer can be complicated. Read this blog again or listen to our podcast on invasive breast cancer and let the details of this condition sink in further. You have done a great job up to this point in educating yourself about breast cancer. Now pray, prepare questions and allow your doctor to devise an effective treatment plan that helps lead you on a personalized path to a cure. Remember, in general most women with invasive breast cancer will require chemotherapy. There are also some hormonal properties to your breast biopsy that can not only help personalize your treatment options, but also predict the success of a cure. The most favorable breast biopsy is positive for estrogen and progesterone, but negative for HER2. It also is well differentiated. Regardless of your biopsy results, know that God desires to heal you from the inside out. Your journey in the battle against cancer is beginning, but I am excited about your future.

REFERENCES

1. Noone AM, Cronin KA, Altekruse SF, Howlader N, Lewis DR, Petkov VI, Penberthy L. Cancer Incidence and Survival Trends by Subtype Using Data from the Surveillance Epidemiology and End Results Program, 1992-2013. Cancer Epidemiol Biomarkers Prev. 2017 Apr;26(4):632-641.

2. Li CI, Uribe DJ, Daling JR. Clinical characteristics of different histologic types of breast cancer. Br J Cancer. 2005 Oct 31;93(9):1046-52.