Cancer spreads mostly through lymphatics or less so by hematogenous spread. Most often the lymphatic drainage from a particular organ goes to a local catchment area consisting of the lymph nodes. If a particular organ is cancerous, the lymphatics carrying the cancerous cells lodge first in the lymph nodes which become the site of metastasis. Since, the lymphatics coming from a particular organ does not come back to that site again, the metastasis is not possible at the primary site. Theoretically, it may be argued that the lymphatics do connect to the blood vessel and again through blood supply the cancerous cells coming from a cancerous organ can come back to the primary site. Thus, from a primary tumor, metastasis can occur in other organs through the above mentioned mechanisms. However, the metastasis occuring in the primary site even if it happens is not differentiated from the primary since the nature of the primary in terms of cancerous parenchyma or tissue is similar to that of the secondary or metastasis.

The secondary sites of metastasis for a particular primary tumor may have receptors. However, the primary cancerous lesion may not have receptors for its own. Based on this concept a metastasis may not occur at the primary site before or even after surgical removal of the primary. However, this concept needs further study and confirmation.

Hi

In breast cancer (and I'm sure many solid tissue cancers) local recurrence can be a commonality. If for example a breast tumour was removed by surgery (mastectomy) then there is a 5% to 40% chance of the tumour re-appearing at the same primary site at a later time (this local recurrence is not the same as lymph node mets). Whether local recurrence is indeed secondary cancer is perhaps a point that needs to be judged on a case by case basis.

Hope this is of some use.

Al

A tendence may exist to the surgical removal of primary tumor offering advantages even in cases of disseminated tumors; surprising evidence exists on the beneficial effect of things such as surgery on the periclavicular tumor-affected lymph nodes in Breast cancer patients. Looking for metastasis with a Lancet in your hand was considered anti-oncology not too long ago, and also, in some cases, added to the possibility of initial surgery missing part of the tumor, a new primary arising in the same region as the initial tumor is an actual danger, as for example in the "Field carcinogenesis" of Head & Neck and other tobacco-related respiratory tract tumors. Old popular stories existed about a tumor flare in distant sites after removing the primary, and even when this not a common case, it can happen, and there are explanations for this in the biology of tumor cell growth and metastasis. Surgery is the most curative therapy for cancer, the rest in many cases does add something to surgery, or act as a palliation and in changing a fast growing tumor that would kill the patient into a chronic disease. Regards.

Hello.

I think that a crucial factor in this question is the adequacy of the removal of cancer at the primary site. Therefore, even when clear margins are achieved, there is a possibility of local recurrence, as the current definition of resection margins does not take into account the existence of elements, such as extensive fibrin deposition at the surgical margin, which could host residual disease, undetectable by the pathologist's microscope. As a result, it is not very infrequent to receive after the operation histopathology reports which state that the primary tumor has been completely removed and the patients develop local recurrence, especially when no adjuvant treatment is used.

Thus, based on strictly histopathological definitions, these could be regarded as cases of secondary metastasis to the primary sites, even the rationale above is in contrast with the latter.

Hello .

I think we need to differentiate between local recurrence of of excised tumor and metastatic, to me , local recurrence of tumor mostly happens due to inadequate excision of the tumor ( ie the margins are not free of tumor cells , not only in macro but also in microscopic level).

Regarding the metastatic tumor, the previous colleagues covered it very nicely.

Only this point I wanted to clarify ,

An additional possibility is a second primary in the same organ where the first tumor arised, think in the "Field carcinogenesis" by the combined effects of tobacco and alcohol all over the respiratory tract, and the second primaries in Breast and other cancers, sometimes with the same histology, sometimes with an slightly of fully different pathology, and tumors linked to the impaired immunity by some infectious diseases or in Hematologic malignancies.

As is generally believed at the primary site, it is the re-occurrence of remnants of primary cancer cells due known or unknown surgical excision lapses. However, possibly due to multiple factors such as exhaustion of local resources, complex or hostile alterations in local micro-environment, immunologic overpower due to surgical bulk removal, hemodynamic and drainage considerations coupled with homing receptors and preferential metastatic predilection seem not to allow formation of secondaries at the primary site. The only chance for such an eventuality appears to be complete reversal of flow from regional lymph nodes via afferent lymphatics back to the primary site.

There's a recent NCCN Webinar in the Women's Health series, on Surgical issues in Breast cancer that deals with this subject, and also an article by Ani I et al, in BJU about results with positive or negative surgical margins in patients having had Partial Nephrectomy for Renal Cancer, that suggests no Statistically Significant Survival difference with positive or negative Surgical margins. PubMed 23305148, I cite this just as examples, but the situation in an individual case may differ. Salut +

Dear Jose,

It is very important to understand the difference between local recurrence due to inadequate excision of surgical margins and metastases as also pointed out by

Mohammed Al-Khawalde.

Yeah!: I'm perfectly aware of the difference between local recurrence and distant or in organ metastasis, can't imagine what may have make you thing otherwise.

I think the question to be addressed is why the secondary metastasis does non occur at the primary site after complete removal of primary tumor and not the local reoccerrence.