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The Body Electric
ing hierarchy. A few years ago, for example, I met a young research
fellow at the National Cancer Institute who wanted to study the re-
generation-cancer link. He even showed me his proposal, an excellent
one. I told him he was asking for trouble if he submitted it to NCI, but
he said his boss approved and he was sure he'd get the grant. A month
later he was forced out of the institute, and the project has never been
funded. Nevertheless, supporting evidence, from research on the periph-
ery, does exist.
Since regeneration can't occur without the stimulus and control of
nerves, one would expect them to exert some controlling effect on can-
cer. They apparently do. As far back as the 1920s, several experimenters
implanted tumors into denervated areas. Without exception the cancer
cells took root better and grew faster than where the nerves were intact.
The early work on this point was criticized on the grounds that denerva-
tion might have reduced the efficiency of the circulatory system, which
in turn would have enhanced malignant growth. Then in the mid-1950s
and 1960s more sophisticated techniques established the same rela-
tionship. Absence of nerves accelerated tumor growth, and variations in
the blood supply had no significant effect.
Further evidence confirming Rose's conclusion that regenerative con-
trols caused tumors to regress came from a series of experiments by F.
Seilern-Aspang and K. Kratochwil of the Austrian Cancer Research In-
stitute in 1962 and 1963. They worked on salamanders, but instead of
implanting frog tumor cells they induced skin cancer with large, re-
peated applications of carcinogenic
chemicals. With persistence they
eventually got tumors that would invade subsurface tissues, metastasize,
and kill the animals. In one series they applied the carcinogen to the
base of the tail; the primary tumor formed there, and metastases ap-
peared at random in the rest of the body. If they then amputated the
tail, leaving the primary tumor intact, this malignancy would disappear
as the tail regrew. Cell studies showed that it didn't die or degenerate
but apparently reverted to normal skin. Furthermore, all the secondary
tumors vanished, too, as though they were being operated by remote
control from the main one. The salamander ended up with a new tail
and no cancer. However, if the primary tumor was at a distant point on
the body, amputation of the tail had no effect. Even though the tail
regenerated, the main cancer and its offshoots all progressed, and the
animal died.
This research, combined with Rose's, indicates that regeneration near
a primary
tumor can make it regress by reverting to its normal
tissue
type.
I doubt that there's anything special about legs or tails; I would