With few exceptions, cancers arise from our own DNA. I say with few exceptions because some cancers have viral triggers. A common example is cancers of the cervix, and in modern times, cancer of the throat, anus and penis all the result of infection with HPV. The remainder of cancers are the results of damage to our own DNA. The “monster,” cancer, is already within us from the moment of our birth. It only takes some damage to that DNA for it to rear its ugly head – ready to take us down the River Styx.
I’m pondering cancer this evening because one of my friends asked me today whether I thought we would ever have a cure for all cancers. The cynical pessimist in me says, “most likely not.” The “Star Trek IV – The Voyage Home” optimist in me says, “Yes, but it will be a long wait.”
I referred my friend to Sidhartha Mukherjee’s superb book “The Emperor of All Maladies.” If you want to understand cancer without enrolling in undergraduate Genetics classes and then going to medical school and possibly doing an Oncology Fellowship after your certification in Internal Medicine, this is the book for you. It is written for non-clinical folk, but I suspect that those of us with such training will appreciate nuances that others will not. It doesn’t matter, if you read this book, you will know more about cancer than 99% of people who haven’t read it.
With all that said, permit me to explain cancer by way of literary metaphor. One of my favorite poems from high school literature is one well-known to most folks from the pen of Robert Frost. The poem is titled “Fire and Ice.” It goes like this:
Some say the world will end in fire,
Some say in ice.
From what I’ve tasted of desire
I hold with those who favor fire.
But if it had to perish twice,
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice.
Now, you will likely recall that our DNA is organized in little packets called chromosomes. Our chromosomes, like the couplets in this poem, are paired. With the proper noxious stimulus, the chromosomes can be damaged – cutting a section off, for instance. The resulting chromosome fragment(s) can find a home on another chromosome where they may or may not make sense. For example, let’s say that the chromosome that says, “But if it had to perish twice,” got broken into fragments that said, “But if it had,” and “to perish twice.” Then let’s say that the second fragment got spliced to the chromosome that says, “From what I’ve tasted of desire.” The altered chromosome would read, “From what I’ve tasted of desire to perish twice.” It wouldn’t make sense. But, if the second fragment got spiced to the chromosome that says, “Is also great” the new chromosome would say “Is also great to perish twice.” That might make some sort of sense.
Something like that happens to our DNA as a result of carcinogenic chemicals, high-energy particles (x-rays, gamma-rays) striking our cells, and other noxious stimuli. Some kinds of DNA injury are reparable because DNA has two strands that complement one another. But major injury that results in chromosomal fragmentation, including deletions of chunks of DNA may not be reparable. If the fragments or fragment rearrangements spell nonsense, then nothing bad may happen, but if the fragments and/or rearrangements can be translated into an aberrant protein, then the altered protein may confer special properties on the affected cell. A cell that was programmed to age and die may become immortal because it has a new protein that confers immortality. A cell that was programmed to live a sedentary existence may now become mobile and able to not only reproduce but move about the body. A cell that was never meant to reproduce may suddenly become capable of copying itself over and over forever. And so, our own DNA, damaged and healed in an abnormal way, is the cradle of most cancers.
Will we ever be able to cure all cancers? Maybe, but if so, not in my lifetime. And maybe not if the world first ends in Fire or perhaps Ice.