INFORMATION FOR MEDICAL PROFESSIONALSOVERVIEW OF TISSUE NECROSIS:
DELAYED RADIATION TREATMENT DAMAGE
Cancer Treatment
How Does Radiation Work
Kinds of Radiation Damage
CANCER TREATMENT
Modern treatment of cancer often involves a combination or selection of therapies:
surgery to remove diseased tissue, and chemotherapy and/or radiation to destroy cancer cells and hopefully
prevent metastasis, the spreading of cancer to a different location in the body.
Surgery alone is traumatic to the body, involving removal of the tumor,
as well as damage to the tissue around it. The surgeon often has to cut through healthy
tissue to reach the tumor. Even on the skin, enough healthy tissue around the cancerous site has to
be removed to ensure that there are no cancerous cells left behind to cause the tumor to recur.
Thus, Moh’s surgery, where thin layers of skin are repeatedly removed and biopsied until a layer is
‘clean’ is often used, especially when a skin cancer recurs—the surgeon did not ‘get it all’ the first time.
The theory of chemotherapy is to provide a carefully calculated systemic poison
to the patient. Cancer cells grow faster than normal cells—they are ‘greedy’ in their consumption of
nutrients. Because of their accelerated metabolism, they grab and process the chemotherapy drugs more
quickly than the rest of the body. This is why chemotherapy can be an effective way to scout out and
destroy rogue cells in the body—it doesn’t matter where they are hiding, their ‘me first’ attitude puts
them directly in the line of fire.
Radiation enables the physician to treat ‘hard to reach’ parts of the body, or
places where the damage of reaching the tumor might exceed the benefit of excising it. It kills cells
outright, inflicting lethal damage to ensure later cell death, stop cell replication, or inhibit collagen
formation. Since tumor cells are less capable of DNA repair than healthy cells, they die off more quickly.
Radiation may be the primary treatment, or it can be part of a treatment program involving chemotherapy and/or surgery.
Often, radiation is used to shrink tumor size to make surgery easier. At other times, it is used as a
post-surgical treatment to finish destroying residual cancer at the primary site. Although physicians
are careful to minimize damage to healthy tissue, it is often unavoidable.
Tissue death is the direct result of exposure to radiation. When radiation doses
are divided (fractionated) and administered over time, each dose damages cellular DNA. Part of the strategy
is to selectively treat cancer cells, knowing there will invariably be some “overflow.” Whether damage
is to healthy tissue or tumor, radiation results in swelling and blood flow restriction in the immediate
area of treatment. If radioactive “seeds” are implanted, tumor shrinkage may result in a greater amount of
tissue being exposed than originally planned. Close monitoring throughout radiation treatment is required
to minimize damage to healthy tissues.
Although the greatest risk for cancer patients is inadequate treatment, the limits
of the human body to endure both the immediate acute and long term late effects of radiation often force
the physician to restrict exposure. Acute complications, direct cellular DNA damage, and cell death are
self-limiting and seldom restrict the dosage limit of radiation treatment.
It is difficult to calculate the optimal dosage to maximize the benefit to damage
ratio. Although high radiation dosages may be able to destroy all malignancies, the body has a limited
tolerance to radiation. Certain cellular messengers (cytokines), which appear at the beginning of radiation,
seem to be associated with late radiation damage. The extent and nature of the damage cannot be accurately
predicted.
| To date, the most successful treatment for this radiation injury is Hyperbaric Oxygen Therapy.
HBOT increases the formation of new blood vessels into radiation damaged tissue and reduces the formation
of thickened scar tissue (fibrosis). |
HOW DOES RADIATION WORK?
When exposed to radiation, three cellular chemical changes occur:
• the cellular protein structure is damaged, leading to cell death,
• lipid peroxidation damages cell walls and energy storage,
• and DNA damage.
Cellular DNA is the critical target—the cell being most sensitive to radiation
damage just before mitosis (where it grows by splitting into two cells). The faster cells are dividing
(characteristic of cancer), the more sensitive they are to radiation damage. Cellular specialization
decreases sensitivity; i.e., undifferentiated stem cells would be more susceptible to damage than cells
of a specific organ.
Connective tissue, including the lining of the blood vessels, is less sensitive
than cells in the process of dividing, but more sensitive than those which have completed the process.
Damage to the blood vessels—swelling, degeneration, and vessel obliteration—may be a cause of delayed
tissue death from radiation (necrosis) and probably accounts for the poor tissue healing observed when
subsequent surgery is required.
WHAT KINDS OF DAMAGE CAN RADIATION CAUSE?
All radiation damage is not immediately apparent. Symptoms worsen over a long
period of time, but damage begins when treatment starts. When damaged cells fail to reproduce and a
restricted blood supply limits the ability of otherwise normal cells to grow and divide, the supportive
collagen is lost, and tissue thickens and becomes stiff (fibrosis).
Much tissue damage seems to originate in the destruction of the blood vessels
serving the tissues, with the degree of premature aging, scarring, and ateriosclerosis within the vessels
dependent on the type of radiation, exposure location and quantity, and individual patient factors.
Helbach (1988) identified four types of damage resulting from radiation treatment:
1) The acute period—the first 6 months. Organ damage
accumulates, often with symptoms.
2) The subacute period—the second 6 months. The body
recovers from the acute period, but permanent tissue damage not only persists, it becomes worse.
3) The chronic period—the second to fifth year.
Residual damage continues to worsen. Capillaries and small blood vessels deteriorate causing a reduction
in the delivery of oxygen to the body, damage to organ function, and reduced infection resistance.
4) The late clinical period—after the fifth post-radiation
year. Chronic period damage continues, along with premature aging and the development of new
radiation-induced cancers (as opposed to recurrence of the original cancer).
The death of tissue
(necrosis) during this period of time results from the radiation treatment years before.Thus, years after
the cancer has been cured, radiation necrosis can be debilitating.
Blood vessels are not the only part of the body damaged by radiation. The skin,
underlying soft tissues, and mucosal lining of the digestive and genitourinary tracts, may all suffer.
Initially, the skin may become dry and itchy, red, peeling, weepy, and tender. Later, the skin may darken
and atrophy (shrink) in affected areas, and become more prone to develop hard-to-heal ulcers in response
to minor injuries.
Most cancer patients experience pain, either because of the disease or as a result of radiation treatment. This secondary, treatment-induced pain is present up to 25% of the time.
| Hyperbaric oxygen therapy, which has been described as an effective treatment for blood in the urine or intestines and bone death (necrosis), is also effective in treating pain from radiation of soft tissue and pelvic organs, rectal bleeding, multiple surgeries, and non-infected tissue death. |
HBOT provides the oxygen support needed for reduction of vascular-damage pain,
growth of blood vessels, wound healing and, in many cases, providing cure, rather than just symptomatic relief.
©2008 Florida Oxygen
|
|
You are on the medical professional information portion of the site. Click
for patient information.
|
|
