TRYPTOPHAN AND BREAST CANCER

Lily, I don't know anything about this, although the study looks interesting. I am not sure that supplementing would do anything though

Two things come to mind. One is, tryptophan (TRP) is converted to seratonin and then melatonin. So lower levels of tryptophan may correlate with lower levels of melatonin. And lower levels of melatonin have been implicated in higher risk of breast cancer (nurses and others working night shift have elevated BC risk due to light at night interfering with melatonin production). Secondly, the paper said this: "The concentration of TRP can also influence levels of tyrosine (TYR), an important amino acid that is converted to levodopa by the enzyme tyrosine hydroxylase (TH) by dopaminergic cells in the brain [21]. In the adrenal medulla, tyrosine is converted into catecholamine hormones, norepinephrine and epinephrine." If they mean that higher TRP levels lowers levels of tyrosine and thus catecholamines, that could explain a protective effect. These are stress hormones that may drive BC progression. Beta blockers such as propranolol have been shown in some studies to reduce risk of recurrence for BC or improve overall survival. Studies have been mixed, but many have shown a positive benefit, and the mechanism is by blocking the receptors for norepinephrine and epinephrine on cancer cells (they are called beta-adrenergic receptors). So if TRP is depleted it may allow higher levels of these catecholamines, which may be driving cancer growth. But the study doesn't specifically say lower levels of TRP allow or cause higher levels of tyrosine, so I may be totally off.

I also found this study, which is interesting:

Indoleamine 2,3-Dioxygenase Activity during Fulvestrant Therapy for Aromatase Inhibitor-Resistant Metastatic Breast Cancer

"We evaluated the clinical significance of indoleamine 2,3-dioxygenase (IDO) during fulvestrant therapy for aromatase inhibitor (AI)-resistant metastatic breast cancer. IDO activity can be measured by the tryptophan (Trp)/kynurenine (Kyn) ratio. Trp and Kyn were measured with high performance liquid chromatography (HPLC). Patients with AI resistant metastatic breast cancer had a 28.6% response rate to fulvestrant therapy, and the clinical benefit rate was 76.2%. AI-resistant metastatic breast cancer patients with distant metastases had a lower serum Trp/Kyn level than patients who had local recurrences. During fulvestrant therapy, IDO activity significantly decreased in the fulvestrant responder group compared to that in the fulvestrant non-responder group. During fulvestrant therapy, the IDO activity correlated with the number of metastatic lesions. These results suggest that measuring the Trp/Kyn ratio is useful for evaluating immunological metastatic status during endocrine therapy."

http://www.ncbi.nlm.nih.gov/pubmed/26489554

It's so maddening, all the side effects from pretty much every form of treatment. I was going to mention that high dose vitamin D has been proven to give some relief to musculoskelatal pain, but that isn't what's troubling you. My heart goes out to you and I hope you can find something to bring you relief.