change of the state) is the spread of cancer
from its primary site to other places in the body" Cancer
cells can break away from a primary
tumor, penetrate into lymphatic
vessels, circulate through the bloodstream, and grow in a
distant focus (metastasize) in normal tissues elsewhere in the
body. - Wikipedia.org
The term metastasis can evoke fear in
patients, likely because it's associated with very poor clinical
prognosis in many so-called solid cancers. E.g., breast, colon, lung cancer, etc.
Metastasis of a lymphoma
seems a misnomer - that is, an interpretation known not to be true. The normal behavior of lymphocytes (the cell of origin of lymphomas) is to travel or migrate in the blood and lymphatic tissue in order to fight infection.
Click the image to enlarge picture showing migration of lymphocytes.
Therefore, "migration" or "extranodal" seem better terms for the spread of a lymphoma than "metastasis," because the change in location does not necessarily mean a profound "change in the behavior of the cancerous cells," that is, from slow growing to rapidly multiplying, or to treatment-resistant disease.
Note: it's common for lymphomas to show up (present) in the blood, bone marrow, and lymphatic organs. The bone marrow is a nursery for blood cells. Thus, the existence of lymphoma cells in the marrow is generally expected, but often reversible.
Some types of lymphoma first present in the skin
(Cutaneous), the stomach (Gastric), the lung (Pulmonary), bone (Osteo), eye
(Orbital) and other regions. Gastric MALT, a marginal zone lymphoma, tends to stay localized in the gastric mucosal tissue, but it can spread to other areas. That said, scientists and radiologists may use the term metastasis or metastatic behavior when describing changes in the location of lymphomas (as shown in the abstracts below).
The important question seems to be: does the metastatic behavior of a lymphoma have the same clinical connotation as for solid cancers? Fortunately, the answer is often that
the spread to a new location does not necessarily predict sensitivity of the lymphoma cells to treatment or the potential for
a favorable long-term outcome.
~ KarlS (layperson perspective)
"Lymphoma cells are derived from normal lymphocytes and
therefore their metastatic behavior is probably based on
mechanisms of migration of these normal progenitors [cells
Several adhesion molecules that are involved in this normal
migration, have been identified. These include the 'lymph node
homing receptors' and the leukocyte (beta 2) integrins. The
limited evidence available for a role of these molecules in
lymphoma metastasis is reviewed here. Recently, the regulation of
the activity of adhesion molecules was shown to be of pivotal
importance for the control of leukocyte traffic. The
implications of these findings for lymphoma metastasis are
Adhesion molecules in lymphoma metastasis.
Cancer Biol. 1993 Oct;4(5):285-92. Review.
The site of origin of lymphoid tissue is an important determinant
of lymphocyte migration patterns. The association of
gastrointestinal (GI) and Waldeyer's ring lymphoma and the unique
lymphocyte migration pattern of gut-associated lymphoid tissue
(GALT) have been previously described.
To establish whether predictive clinical patterns of disease occur
in localized Non-Hodgkin's lymphoma, survival and relapse patterns
for 496 patients with stage I and II non-Hodgkin's lymphoma (NHL)
treated with loco-regional irradiation (XRT) alone were
We identified 139 patients with GALT lymphoma (defined as arising
from primitive gut and including Waldeyers' ring, thyroid, and GI
lymphomas) and 87 patients with extranodal non-gut-associated
Survival and relapse data were assessed in multifactorial analysis
to correct for previously identified other prognostic
GALT lymphomas (GALT-L) have a survival advantage compared with
other ENL (P = .017) independent of stage and histology. A
difference in distant relapse (DR) rate between GALT-L and other
ENL (P = .0002) was also identified. The presentation site of
localized extranodal NHL is predictive of clinical behavior and is
an independent determinant of outcome. This may be an expression
of lymphocytic origin and determinants of migration patterns
Patterns of disease in localized extranodal lymphomas.
Clin Oncol. 1987 Jun;5(6):875-80.