|
The processes involved in metastasis are highly complex, and still incompletely understood despite a great deal of research. This ongoing research is motivated by the fact that metastasis is almost always what causes cancer death.
"Modern surgery and/or radiation therapy successfully eradicates the majority of primary tumors, but the inability to control metastases is the principal reason why there has been little progress in reducing cancer mortality in the last 30 years."1 This statement, written more than a decade ago, still holds an unfortunate degree of truth, and explains why prognosis typically is based on degree of, or likelihood of, metastasis in a case.
The majority of lethal cancers involve blood circulation metastasis. Currently, there is a good prognosis with prompt treatment in cancers limited to local lymph node spread, but with increasingly distant lymphogenous metastasis the survival rate decreases, especially as the neoplastic cells eventually join the bloodstream.
Massage therapy and associated modalities such as hydrotherapy and remedial exercise can act as strong stimuli to blood and lymph flow, so it is important to take a serious look at whether massage therapy could promote metastatic processes.
The set of events and possibilities in distant metastasis is complex. At each stage the body's defense systems are capable of eradicating the malignant cells. Evidence suggests that far more are killed than survive. The
"successful" cells overcome a harrowing set of challenges. In one study (Fidler,
1978)4 where injected radiolabeled cancer cells were monitored, most cells were destroyed within 24 hours, and after three days less than 0.1 percent remained viable. This result has been substantiated in several high-quality
studies.5
|
Events in Distant
Metastasis2,3
Hematogenous Spread
-
Cell shedding from the primary tumor.
-
Poor quality of tumor blood vessels facilitates permeation; cells pass through the blood vessel walls into the
lumina, and hence the blood.
-
Transport of tumor cells in the bloodstream. Cells may aggregate, increasing their chance of success.
-
Impact in a capillary network, usually the first encountered.
-
Destruction, or adherence to blood vessel walls, or continued travel to subsequent sites.
-
Penetration through capillary walls to tissue
interstitium.
-
Secondary tumor growth.
Lymphogenous Spread
-
Cell shedding from the primary tumor.
-
Movement of cells into the interstitial space of the host or nearby structures.
-
Cells penetrate into lymph capillaries, or are picked up by them, and enter the small lymph vessels.
-
Travel to regional lymph nodes.
-
Destruction by immune system cells or proliferation in the node. Note that cells can enter the bloodstream via the nodal capillaries.
-
Passage to right lymphatic and thoracic ducts.
-
Entry to bloodstream. See Hematogenous Spread.
|
|
We can only surmise the role massage therapy could play in these events, since research on the subject has not been conducted. Clinically based consultation with physicians, and careful examination of known data, permits some presumably reasonable conclusions to be drawn. It must be noted, however, that the current lack of certain knowledge may pose some degree of risk to our clients.
We will consider the metastasis process to be occurring in three principal stages, and examine the potential impact of massage therapy at each stage.
|
Stage 1: Cell Shedding From The Primary Tumor
Tumor cells for the various cancer types have their own characteristic rates and time frames for metastatic development. It is possible that only a certain percentage of cells are capable of the splitting off mechanism, and that this percentage varies in different cancers. These factors are beyond the control of the massage therapist.
The question remains, however: Could direct pressure or another strong stimulus, such as intense hydrotherapy, enhance the potential for cell shedding from a malignant tumor? One instructive reference was found in the physiotherapy context.
"This process [of cancerous cells entering the bloodstream] is influenced by several factors, such as biomechanical processes or gross mechanical
manipulation, which can drive a large number of cells into circulation."6 The implication is that sufficient direct pressure will traumatize the tumor and promote release of cells. It may also be inferred by
"biomechanical processes" that an intense movement modality (for example, passive forced stretching) or a highly stimulating local hydrotherapy application might be unsafe. |
|
In response to a question from a physician, this medical opinion was offered in the Journal of the American Medical Association in 1977:
"I firmly believe that heat and massage should not be used if there is any possibility that a primary or metastatic neoplasm exists in the skin or subcutaneous tissue at the site of application."7
This is an old source, but it reflects a current concern. The implication is that the closer the cancer is to the skin surface, the greater the risk from massage therapy.
It would be more satisfying to be able to consider a larger volume of research and opinion. However, the possibility clearly exists that some components of massage treatment, if applied locally and with sufficient intensity, especially to a superficial tumor, could provoke cell shedding.
|