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84 | SPRING 2013
the risks of metastasis and local recurrence. This approach
is not appropriate in every case, and its use is influenced by
tumor type, location and the degree of metastasis. Tumors
located in vital organs such as the brain, lungs and liver offer
additional challenges for surgical resection; their removal
may be life threatening or may constitute an unacceptable
risk to surrounding structures. Some cancers, such as
those involving blood or bone marrow, are not amenable
to surgery due to the nature of the tissue. In these cases,
chemotherapy and radiation are often used.
Chemotherapy
Chemotherapy refers to the use of cytotoxic drugs (drugs
toxic to cells) to attempt to limit or stop tumor growth.
The type of chemotherapeutic drugs used and the duration
of treatment vary. Chemotherapeutic agents are delivered
systemically, and many do not target tumor cells specifically;
rather, they primarily affect rapidly proliferating cells.
Chemotherapy may involve one or more drugs and is
often employed to kill tumor cells left behind after surgery
or tumors located in inoperable locations. Chemotherapy
may also be administered preoperatively when reducing
tumor size will make removal safer and/or more effective.
Side effects are systemic and may include fatigue, nausea,
bleeding problems, diarrhea, reduced stamina, hair loss
and immunosuppression. Some new agents that are more
discriminating and not cytotoxic are available. An example
is the use of monoclonal antibodies, which target proteins
expressed in certain cancer cells.
Radiation
Radiation therapy uses focused, high-energy ionizing
radiation to kill cancer cells. Radiation impacts DNA
directly and/or induces formation of free radicals that alter
DNA activity, leading to cell death. Because therapeutic
ionizing radiation is delivered only to the site of the
tumor, systemic side effects are less common than with
chemotherapy. However, acute tissue damage (radiation
burns) can occur, as well as delayed effects such as
breakdown of local tissue or scarring that may appear
months or years after treatment.
Bone Marrow Transplantation
For certain blood-based cancers, bone marrow transplantation
may be used. In these cases, the patient undergoes bone
marrow ablation, which kills the cancer cells along with
healthy marrow. Marrow stem cells derived from either the
patient or a donor are then transplanted, with the goal of
growing cancer-free bone marrow.
Connection to Diving
It is important to state that diving is not associated with
promoting or enhancing cancer growth.
Medical fitness to dive begins with the premise that a
diver has the capacity to care for himself and assist others.
Note that this starting point does not address physically
disabled people, a group for whom such criteria are
legitimately altered due to special procedures and methods
of support. A cardinal rule of safe diving is that divers
should dive within the parameters of their skills, training
and physical ability. In this context, wellness encompasses
the ability to handle the physical rigors of diving as well as
mental and emotional readiness for the potential challenges
of the environment.
With regard to medical fitness for diving with cancer, an
important consideration is how the cancer affects or has
the potential to affect critical organ systems in ways that
may lead to injury, incapacitation or death. Factors such as
fatigue, immunosuppression, bleeding and the potential need
for urgent medical support require strong consideration.
Conservative postsurgical guidelines should be followed
prior to a return to water sports. These include complete
healing of the skin, regaining physical strength and
stamina and medical clearance from the treating physician.
Complete healing of wounds is critically important since
both freshwater and saltwater environments are filled with
bacteria that can infect open wounds.
Cancers that affect the following body systems are of
particular concern to physicians who evaluate divers.
Brain
The health concerns associated with brain tumors include
a potential for seizures, bleeding into the brain, sudden
loss of consciousness, altered mental status, changes in
behavior and diminished cognitive ability. For these reasons,
recreational divers are advised to refrain from diving until
their neurologist or neurosurgeon clears them. The clearance
process should involve careful consideration of the diver’s
likelihood for sudden neurological changes or incapacitation.
The prognosis of brain cancer is determined by the
location, tumor type and extent of tissue involvement.
Benign tumors that are easily amenable to surgery and
located where removal involves limited damage to
surrounding tissues carry a more favorable prognosis than
malignant tumors that are invasive or located where removal
would necessitate unacceptable risk.
Lungs
As the leading cause of cancer death, lung cancer often holds
a poor prognosis. Treatment involves a variety of modalities
that include chemotherapy, radiation and surgery. Tumors
can cause inflammation of lung tissue, compress airways
(which could predispose divers to air trapping) and decrease
pulmonary function. Radiation therapy can cause lung-tissue
inflammation, and surgery can cause scarring and reduce
the quantity of available lung tissue. All of these issues weigh