Radiation : thecomplete carcinogen

[Guest guest]

Radiation Causes Bone Loss by Ralph Moss, PhD

 

The scientific world has been shaken by a report from

Clemson Univer.sity that a single therapeutic dose of

radiation can cause appreciable bone loss. Senior

author Ted Bateman, PhD, a professor of

bioengineering, and his South Carolina colleagues

showed that when mice were given a dose of just two Gy

(two gray, a radiation dosage formerly designated as

200 rads), between 29 and 39 percent of their interior

bone mass was destroyed.

 

It did not particularly matter which kind of radiation

the mice were exposed to. Gamma rays, protons,

high-speed carbon and iron nuclei all had a similar

and markedly destructive effect. Dr. Bateman and his

colleagues reached these figures by creating 3D

computer scans of the spongy interior of the bones and

then calculating how much bone mass these irradiated

mice had lost compared to a control group.

 

" We were surprised at how large the difference in bone

mass was, " Dr. Bateman told the weekly magazine, New

Scientist (Barry 2006).

 

Two Gy of radiation is similar to a single therapeutic

dose of radiation given to human cancer patients,

while a full course of therapeutic radiation typically

delivers as much as 70 or even 80 Gy.

It had previously been known that patients receiving

therapeutic radiation suffered some bone loss and were

put at a greater risk of fractures.

But until n/o/w it was unknown that just a single dose

of radiation could trigger such severe bone loss. This

news is doubly disturbing since chemotherapy (often

n/o/w given with radiation as part of a one-two punch)

can also independently cause bone loss. The cumulative

effects of radiation and chemotherapy delivered to the

same patient may therefore be significantly more

damaging.

 

The Clemson scientists demonstrated what they called

" profound changes in trabecular architecture. " (The

term " trabecular " describes the microscopic bony

latticework that characterizes the interior of

skeletal bones. The trabecular pattern of bony tissue

is what gives bones their structural strength.)

 

Significant losses in bone volume were observed for

the four types of radiation that were studied: gamma

(volume down 29 percent), proton (down 35 percent),

carbon (down 39 percent), and iron (down 34 percent).

Several measurements of bone health, including

trabecular connectivity, density,thickness, spacing,

and number were also adversely affected.

 

" These data have clear implications for clinical

radiotherapy, " the Clemson scientists said, " in that

bone loss in an animal model has been demonstrated at

low doses " (ibid.)

 

Dr. Bateman agreed, however, that making a direct

extrapolation of these findings to humans could be

difficult. The bones of the mice in the experiment

were still growing, making them more susceptible to

radiation damage. (This is also the case in you/ng

human patients.) Although the Clemson findings have

caused a stir particularly in space research circles,

NASA's chief radiation health officer, Dr. Frank

Cucinotta, pointed out that the gamma ray dose in

these mouse experiments was 40 times greater than

space station astronauts would experience over a

period of months, and 2 to 4 times what astronauts on

a Mars mission would encounter. However, astronauts

are also exposed to high-energy and iron nuclei in

addition to gamma radiation.

 

Bone Death: A Long History

 

It has been known for quite some time that radiation

could cause " serious and permanent injuries " to

growing bones as well as localized but incapacitating

diseases (Fajardo 2001: 365). In fact, the real

surprise in the latest study was that relatively small

doses caused such a significant amount of damage.

 

The basic concept of 'bone death' was probably known

to the ancient Greek physician, Hippocrates. Necrosis

of the bone (i.e., osteonecrosis) was fully described

as early as 1794. In 1903, just a few years after the

1895 discovery of X-rays, the German surgeon Georg

Clemens Perthes (1869-1927) exposed one wing of a

day-old chicken to X-rays.

Just 12 days later he noted that growth of the

irradiated wing was retarded and that the feathers

were abnormally formed. In 1905, two French

scientists, Joseph Recamier and Louis Mathieu

Tribondeau (1872-1918), described similar growth

retardation in kittens.

 

In the intervening decades, various tumors, especially

sarcomas, were found with increased frequency in

patients who had undergone irradiation. James Ewing,

MD (1866-1943), the celebrated American pathologist

(after whom the bone tumor called 'Ewing's sarcoma' is

named), was extremely interested in the reactions of

bones to radiation. He was impressed by the ability of

radiation to shrink the size of bone tumors and, along

with surgery and Coley's toxins (a fever-causing,

mixed bacterial vaccine), to effect prolonged

remissions in some cases (Ewing 1940:370). He

described three patients who had been irradiated for

bone cancers and whose irradiated bones then became

brittle and easily fractured. Ewing also observed

thickening in the outer layer (known as the cortical

plate) of bone at the expense of the marrow cavity and

noted the increased susceptibility of irradiated bones

to infection (Fajardo 2001).

 

The most famous instance of radiation damaging bones,

however, occurred in the first decades of the 20th

century. Industrial engineers learned that by adding a

small amount of radium to a zinc sulfide solution (at

a ratio of 1:30,000) they could create a luminescent

paint that glowed in the dark. This seemed to be a

harmless product. Around the time of World War I,

approximately 2,000 you/ng women in New Jersey were

employed painting the dials of clocks and watches with

luminous paint.

In order to create fine brush tips for this detailed

work they would frequently lick the tip of the

brushes. Over the years, these women either ingested

radium itself or breathed in radon gas in sufficient

quantities to cause serious medical problems for many

of them. A New York dentist, Theodore Blum, DDS, was

the first to observe an unusual number of jaw-bone

injuries in these unfortunate dial painters, a

condition he called 'radium jaw.'

 

The medical examiner of Essex County, NJ, at the time,

Harrison Marland, MD, then became alarmed and launched

a thorough investigation. He found severe anemia in

most of these women. At autopsy, many of these women

had necrosis of the bones, especially the mandible

(lower jaw). Marland also recounted how the damaged

bone marrow, excised osteosarcomas (cancers) of their

bones, or even organs removed at autopsy literally

glowed in the dark (Fajardo 2001: 366). These women

were so radioactive that, even after death, their

bodily organs would fog photographic film!

 

The most incred.ible part of this saga is that despite

the fact that the danger of luminous paint was well

established in the 1920s, it was not until nearly 20

years later - in the run-up to World War II - that

action was finally taken to bar the use of radium in

watch dial paint (Caufield 1989). It was a most

shameful episode in public health, but it did make the

general public aware that radiation could seriously

damage bones and organs.

 

What is the Tolerance Dose?

 

Medical dictionaries define a 'tolerance dose' as the

largest quantity of a substance or treatment that an

organism can endure without exhibiting unfavorable or

injurious effects. The tolerance dose of radiation to

the bones has traditionally been set quite a bit

higher than is implied by the recent Clemson article.

There are many variables, but generally speaking when

the dose is from 70 to 80 Gy the incidence of

osteoradionecrosis (bone death caused by radiation) is

in the range of 14-22 percent. It is 4 percent when

the dose is under 70 Gy. The tolerance dose for the

adult human femur (thigh bone) is said to be 38 to 43

Gy.

 

In the 1950s, Michael Bonfiglio, MD, of the

Univer.sity of Iowa, found a 1.2 to 1.9 percent

increase in the incidence of fractures of the femur

after pelvic irradiation for cancer (Fajardo

2001:373). Among patients who still have their teeth,

the bone necrosis rate caused by radiation is 24

percent. Among those lacking teeth the rate is less -

14 percent. In studies involving patients who still

had teeth, this bony necrosis developed on average 10

months after completion of radiation therapy. In those

without teeth, it occurred on average 22 months later.

 

As noted above, if the bone is growing (as in the

Clemson experiment) the tissues are ultra-sensitive to

radiation. Clinical observations suggest a tolerance

range of 15-30 Gy for growing bones.

 

In conclusion, exposing bone to radiation can result

in four major types of complications: necrosis (a type

of cell death), fractures, severe alterations in bone

growth, and radiation-induced cancers. The topic of

radiation-induced cancers in particular has not

received the attention it deserves.

 

Radiation itself is called a " complete carcinogen, " in

that it can cause the four phases of cancer's

formation: (a) initiation, (b) promotion, ©

progression and (d) metastatic activity of transformed

cells. While radiation-induced tumors of bone are not

common, they do occur, as the case of the radium-dial

painters dramatically showed.

 

Luis Fajardo, MD, who recently retired as a professor

of pathology at Stanford Univer.sity, California, has

documented many such cases. " Irradiation from both

external and internal sources is associated with an

increased risk of osteosarcoma, " or bone cancer, he

wrote in his classic textbook, Radiation Pathology

(Fajardo 2001:128). The minimum latency period for

radium-caused tumors is 3.5 years with a peak time of

about 8 years, although cases were documented as long

as 25 years after initial exposure. Children who

receive radiation for cancers (other than those of

bony origin) are at particular risk if their growing

bones receive large doses of radiation.

 

Although the danger of therapeutic radiation always

seems to come as a surprise to the general public,

most of the risks of radiation to the bone were

recognized soon after Roentgen discovered X-rays. Yet,

astonishingly, in the 21st century some patients

receiving radiation are still not told about the full

extent or true likelihood of the harmful side effects

of radiation therapy.

 

http://www.cancerdecisions.com/102906.html

© 2006 by Ralph Moss, PhD.