The role of nitric oxide in cancer treatment is an area where things are not so clear. Some studies show that it can stimulate tumor promotion and invasion; others that it can improve anti-tumor defenses.

Much work remains to be done, but some studies have suggested nitric oxide does more damage than benefit.

The idea that nitric oxide could be beneficial is based on cancer cell studies rather than clinical studies.

Some studies have suggested that nitric oxide may make resistant cancer cells more sensitive to chemotherapy, and that because of its importance to immunity, nitric oxide may strengthen anti-cancer resistance.

On the other hand, several other studies suggest a negative effect.

For example, it is known that patients with lung cancer have high levels of nitric oxide within the tumor; higher levels are associated with advanced stages of cancer and poor survival.

Nitric oxide is also elevated with other tumors, including glioblastomas, breast cancers, and melanomas, and appears to increase the cancers’ aggressiveness.

Most impressive was the discovery that nitric oxide stimulated cancer stem cells and made tumors more aggressive.

The reason this is so important is that cancer stem cells are the source of tumor growth, invasion, recurrence, and metastasis — that is, everything that makes cancer deadly.

These special cells are also resistant to almost all forms of chemotherapy and radiation.

Other factors leading to increased cancer growth, invasion, and metastasis are also stimulated by higher levels of nitric oxide.