It does sound confusing doesn't it? In this case, I'm referring to 'spread' as a case where cancer cells might not have been fully removed or killed at an original cancer site and lead to a further cancer at the original site. For example, where surgical excision failed to have sufficient clean margins and left some active cancer cells behind. And chemo or radiation failed to kill those cells, etc. In a sense, a cancer caused by cells in the original site that remained viable and active.
As I understand it, the original cancer can have been fully eliminated but a new cancer also form in the same relative area later and would be a local recurrence.
A distant recurrence would be a new cancer, but still a breast cancer, occurring anywhere in the body outside of the original cite, including in non-breast tissue, in but still a breast-type cancer.
Some usage would suggests that the distant recurrence is an example of a cancer that 'spread' to a wholly new area, possibly after a period of dormancy.
But one oncologist, in an article in the New England Journal of Medicine argued that these should be considered new, independent cancer events and totally unrelated to the original cancer and not an example of cancer 'spreading.' He argued that the means by which a cancer, with no evidence of survival, can nonetheless survive and 'recur' in a remote part of the body has never been explained. And that one can simply 'be unlucky' and get cancer more than one time.
The OncotypeDX reports give a probability assessment for 'distant recurrence within 9 years' if the person takes anti-hormone therapy.
I welcome anyone with better or more precise descriptions of the difference between local spread and distant recurrence to please chime in on thus in case I've made it even less clear...
From what I have read, but I may be wrong on this, there are three types of potential recurrences: local, which can be either a recurrence from stray BC cells from the original tumor, or a new primary in the same (ipsilateral) or other (contralateral) breast; regional, such as in lymph nodes or chest wall; or distant meaning metastatic stage 4 BC that may have been from dormant or circulating BC cells. For ER/PR+ HR- BC with lumpectomy there is a tool to determine risk for ipsilateral recurrence with or without hormone, radiation, and chemotherapy treatment: https://www.tuftsmedicalcenter.org/ibtr/ The Oncotype score, and the PREDICT test, provide an estimate only for the risk of a metastatic recurrence. It is my understanding that radiation may be more effective for ipsilateral risk than anti-estrogen drugs, but that AI's or tamoxifen are more effective against new primaries and more distant recurrences by decreasing the estrogen environment favored by ER+ breast cancer. Thank you @callalloo for your research on the OncotypeDX scores!