Bone Marrow is a “Niche” for Tumor Spread

A farmer went out to sow his seed. As he was scattering the seed, some fell along the path, and the birds came and ate it up.  Some fell on rocky places, where it did not have much soil. It sprang up quickly, because the soil was shallow.  But when the sun came up, the plants were scorched, and they withered because they had no root.  Other seed fell among thorns, which grew up and choked the plants. Still other seed fell on good soil, where it produced a crop—a hundred, sixty or thirty times what was sown. (Gospel of St. Matthew 13:3-8)

The word “niche” is commonly found in sciences like biology and evolutionary studies, where the notion of an eco-niche is used to show that some environments are a better “fit” for plant or animal species than others. The above Bible parable shows that this is an old concept. The recognition that seeds grow best in favorable soil probably predates the agricultural revolution that occurred over 10,000 years ago.

In 1889, English surgeon Stephen Paget put forward his “seed and soil” theory that cancer cells (seeds) break away from a tumor and seek a microenvironment that appears most favorable (soil). Less than half a century later, other theories eclipsed Paget’s hypothesis. However, current research increasingly supports his work. Today, there is considerable interest in the idea that bone marrow provides a unique metastatic niche that favorably “contributes to each step of metastasis.”ⁱ

Bone marrow exists in the core of most bones. It is rich in different types of cells and other materials that support tumor implantation, growth, progression, and further spread. There are stem cells that give rise to all other blood cells, which growing tumors need. There are bone growth factors for opportunistic cancer cells to capitalize on. Just as homing pigeons will repeatedly find their way to their starting point, malignant cells that disseminate to and develop in the bone marrow do so by “homing” to marrow and hijacking that niche.ⁱⁱ 

While this may seem discouraging, there is a silver lining. As hijacking processes are better understood, researchers are diligently exploring new therapies that would block these processes. In addition, clinical techniques are making very early detection/diagnosis possible, when chemotherapies and new immunotherapies can have the greatest effect. Finally, when metastatic bone tumors no longer respond to pharmaceuticals, the Sperling Medical Group offers hope for treating existing bone mets. Our Center provides noninvasive MRI-guided Focused Ultrasound (MRgFUS) to destroy bone mets in their preferred niche and deaden the pain-causing nerves. Contact us for more information.

---

ⁱRen G, Esposito M, Kang Y. Bone metastasis and the metastatic niche. J Mol Med (Berl). 2015 Nov;93(11):1203-12.
ⁱⁱShiozawa Y, Eber MR, Berry JE, Taichman RS. Bone marrow as a metastatic niche for disseminated tumor cells from solid tumors. Bonekey Rep. 2015 May 20;4:689.