Cancer survival prospects vary greatly depending on the type, but a general rule is that cancer is lethal after it metastasizes, i.e. after it multiplies within the same organ or spreads to different organs. Symptoms can often be treated to some extent, but a cure is unlikely.
Stepping up to this metastatic cancer treatment challenge, scientists are currently working towards rendering metastatic bone cancer a chronic, rather than lethal, condition. Although promising, this is early-stage laboratory research, and not yet a proven medical treatment.
Other research has used lipid nanoparticles to reduce pancreatic cancer metastasis by 90% in mice. While this is closer to a viable medical treatment, to my knowledge it hasn't moved past the laboratory stage either.
Figuring out a way to prevent cancer metastasis in the first place may increase cancer patient survival rate. Relevant towards this goal is the recent research of Ralf Kemkemer (Max Planck Institute for Metals Research, Germany) and coworkers, who have gained possible insight into the metastatic capacity of cancer cells.
They have demonstrated that disrupting a particular component of the intracellular "skeleton" of pancreatic cancer cells enables them to dramatically alter their shape, and squeeze through small channels. This is relevant to recent research suggesting that cellular deformation (i.e. enabling organ penetration) may facilitate cancer metastasis.
Altering cancer cell movement through restricted geometries.
The scientists etched small channels within a standard, biocompatible polymer film for their cellular deformation studies. The channels were 7 micrometers in the smallest dimension; for reference, their pancreatic cancer cells were approximately 19 micrometers in diameter.
Most (73%) of the cells that interacted with the channels only partially entered the channels. Some of the rest entered, but exited the same way they came or stopped migrating completely, and even fewer traversed the entire length of the channel and exited the other side.
The cells needed to extensively deform in order to enter the channels, and most did not complete the entire journey through a channel. Very different results were observed with cells that were treated with a lipid (sphingosylphosphorylcholine) known to disrupt the intracellular keratin network, a component of the cell "skeleton."
Thirty-three percent of the cells that interacted with the channels migrated through the entire channel. In other words, almost five times as many cells squeezed through the entire length of the channel when they were treated with this lipid, results that are even more remarkable considering that lipid treatment only altered the morphology of roughly half the cells.
Lipid treatment did not significantly impact cell migration rate through the channels, and had little effect on migration rate outside the channels (i.e. in an unconfined environment). Thus, cellular deformation, and not migration rate, facilitated the increased probability of channel traversal.
The scientists further observed that cells moved differently within the channels than within unconfined environments. Specifically, more of the cells moved in a continuous sliding motion, as opposed to a stepwise motion, when they were in the channel.
Thus, the two two major findings of this research are that the lipid sphingosylphosphorylcholine enables pancreatic cancer cells to traverse confined geometries, and affects how the cells move through them. Both of these findings may be relevant towards understanding how cancer cells penetrate organs and invade surrounding tissue.
Future directions.
It's tempting to speculate that anti-cancer drugs which inhibit the ability of cancer cells to change shape may hinder cancer metastasis, and thus increase cancer survival rates. Scientists may begin by hindering the production of sphingosylphosphorylcholine by cancer cells.
Other scientists have also found that extended mechanical stress kills cancer cells. Perhaps brief mechanical stress facilitates metastasis, but extended periods of such stress is unsustainable.
Note that any clinical applications of these research findings are speculative at this point. However, basic research such as that reported herein will always be required for developing new cancer treatments that will eventually make their way to clinical settings.
for more information:
Rolli, C. G., Seufferlein, T., Kemkemer, R., & Spatz, J. P. (2010). Impact of Tumor Cell Cytoskeleton Organization on Invasiveness and Migration: A Microchannel-Based Approach PLoS ONE, 5 (1) DOI: 10.1371/journal.pone.0008726