Breast cancer natural history
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1], Assistant Editor(s)-In-Chief: Jack Khouri
Overview
The natural progression of breast cancer hinges largely on several prognostic factors such as: stage at diagnosis, presence of estrogen and progesterone receptors, and HER2/neu status.
History
There is a theory that up to 22% of small (radiographically detected) breast tumours regress, based on an analysis in a large population.[1] The study is supported by NCI's SEER data.[2]
Prognosis
The prognosis (chance of recovery) and treatment options depend on the following:
- The stage of the cancer (the size of the tumor and whether it is in the breast only or has spread to lymph nodes or other places in the body)
- The type of breast cancer
- Estrogen receptor and progesterone receptor levels in the tumor tissue
- Human epidermal growth factor type 2 receptor (HER2/neu) levels in the tumor tissue
- Whether the tumor tissue is triple negative (cells that do not have estrogen receptors, progesterone receptors, or high levels of HER2/neu)
- How fast the tumor is growing
- How likely the tumor is to recur (come back)
- A woman’s age, general health, and menopausal status (whether a woman is still having menstrual periods)
- Whether the cancer has just been diagnosed or has recurred (come back)
Nottingham Prognostic Index
The Nottingham prognostic index (NPI) is used to determine prognosis following surgery for breast cancer. Its value is calculated using three pathological criteria: the size of the lesion; the number of involved lymph nodes; and the grade of the tumor.
Calculation
The index is calculated using the formula:
- NPI = [0.2 x S] + N + G
Where:
- S is the size of the index lesion in centimetres
- N is the node status: 0 nodes = 1, 1-4 nodes = 2, >4 nodes = 3
- G is the grade of tumour: Grade I =1, Grade II =2, Grade III =3
Interpretation
| Score | 5-year survival |
|---|---|
| >/=2.0 to </=2.4 | 93% |
| >2.4 to </=3.4 | 85% |
| >3.4 to </=5.4 | 70% |
| >5.4 | 50% |
Metastasis
Most people understand breast cancer as something that happens in the breast. However it can metastasise (spread) via lymphatics to nearby lymph nodes, usually those under the arm. That is why surgery for breast cancer always involves some type of surgery for the glands under the arm — either axillary clearance, sampling, or sentinel node biopsy.
Breast cancer can also spread to other parts of the body via blood vessels. So it can spread to the lungs, pleura (the lining of the lungs), liver, brain, and most commonly to the bones. Seventy percent of the time that breast cancer spreads to other locations, it spreads to bone, especially the vertebrae and the long bones of the arms, legs, and ribs. Breast cancer cells "set up house" in the bones and form tumors. Usually when breast cancer spreads to bone, it eats away healthy bone, causing weak spots, where the bones can break easily. That is why breast cancer patients are often seen wearing braces or using a wheelchair, and why they complain about aching bones.
When breast cancer is found in bones, it has usually spread to more than one site. At this stage, it is treatable, often for many years, but it is not curable. Like normal breast cells, these tumors in the bone often thrive on female hormones, especially estrogen. Therefore, the doctor often treats the patient with medicines that lower her estrogen levels.
References
- ↑ Zahl PH, Maehlen J, Welch HG (2008). "The natural history of invasive breast cancers detected by screening mammography". Arch Intern Med. 168 (21): 2311–6. doi:10.1001/archinte.168.21.2311. PMID 19029493.
- ↑ Jatoi I, Anderson WF (2009). "Breast cancer overdiagnosis with screening mammography". Arch Intern Med. 169 (10): 999–1000, author reply 1000-1. doi:10.1001/archinternmed.2009.95. PMC 2768420. PMID 19468099.