Papers listed here have found In a large, Swedish, long-term registry-based study, the use of LT3 did not lead to increased breast cancer incidence, any cancer incidence, all-cause mortality, any cancer mortality, or breast cancer mortality compared with LT4 use. Both these papers are behind paywalls, so I'm sending them to TUK.
THYROID Volume 31, Number 5, 2021 DOI: 10.1089/thy.2020.0388
Liothyronine Use in Hypothyroidism and Its Effects on Cancer and Mortality
Tereza Planck, 1,2Fredric Hedberg, 3,4Jan Calissendorff, 3,4and Anton Nilsson5
Next one
Thanh Duc Hoang, DO1 , Daniel I. Brooks, PhD1 , Antonio Bianco, MD2 , Elizabeth A. Mcaninch, MD3 , Tatiana L. Fonseca, PhD4 , Vinh Q. Mai, DO5 , Mohamed K.M. Shakir, MD5 .
A828 | Journal of the Endocrine Society | doi: 10.1210/jendso/bvab048
There was no significant primary or secondary outcome difference among various genotypes of deiodinase 2. There was no relationship between Hashimoto’s vs. non-Hashimoto’s based on genotypes or likelihood of carrying Thr92AlaD2 polymorphism. Though there was no statistically significant preference for any treatment, numerically more patients with Hashimoto’s preferred DTE and LT4/T3 combination than LT4-monotherapy.
Conclusions: There was no significant difference between hypothyroid patients taking DTE vs. LT4/T3 combination vs. LT4 monotherapy. Numerically, Hashimoto’s patients tended to prefer DTE and LT4/T3 combination. Also, there was no observed relationship between Hashimoto’s and polymorphism
K
Written by
diogenes
Remembering
To view profiles and participate in discussions please or .
We have seen a few claims that levothyroxine (LT4) increases risk of cancer.
If that were the case, we might expect to see combination, desiccated thyroid or T3 therapy reducing the rate of cancer as it reduces exposure to LT4. But that does not seem to be what is reported.
Is this a valid observation and does it have any importance?
Few studies have examined the morbidity and mortality of individuals on long-term LT3 treatment. In this large, longterm registry-based study, including the full adult Swedish population on thyroid hormone replacement therapy, we did not observe any increase in breast cancer incidence, any cancer incidence, all-cause mortality, any cancer mortality, or breast cancer mortality in individuals using LT3 compared with LT4-only treatment. These results were similar after correcting for possible confounders. There was evidence of lower mortality in LT3 users in models adjusting for dose.
This I would read as that T3 addition may be helpful and not worse in mitigating adverse effects, but that related to dose, the T3 situation could be an improvement on T4 alone.
I think it is also the case that at the time of that being originally published, the potency of Thyroid UK was not so well controlled as it could now be.
(I'd have liked to point at the USA desiccated thyroid products as examples of what can be achieved but they have had a pretty bad recent history.)
Probably also didn't help that UK and USA desiccated thyroid products were formulated to different potencies - so one grain of Thyroid BP was less potent than one grain of Thyroid USP. That could have resulted in under-dosing if anyone swapped to Thyroid BP, or over-dosing if they swapped to Thyroid USP, without realising the difference.
It’s a nonsense we should be able to choose what therapy we take; they treat us like babies with no rights over what we put inside ourselves whatsoever - it makes me furious I’m not an infant, I’m an intelligent well informed adult, fully able to decide for myself what thyroid therapy suits me best. They should darn well facilitate it. I’ve paid my NI subs all my adult life supposedly to protect my health. I didn’t pay it to be forced on to an inadequate medication that made me ill all because I have the misfortune to suffer from a thyroid disorder, and be effectively lied to by being led to believe it was the only option - it wasn’t. It’s a scandal.
I think people are missing the essential point here. It is that in therapy there's no real difference between T4, T3, combination T4/T3 and DTE as to outcome, given careful monitoring. Also that genetic differences don't seem to be a factor. And importantly that Hashimoto patients tended to like DTE/T3 combinations more. The relevance and acceptability of DTE has risen one notch. And TUK posters should be grateful for that.
You try getting a diagnosis here in uk that will then lead to any therapy. Years of very low T3 (my results are on earlier posts) have helped me not at all.. even endocrinology consultant paid privately (to speed up seeing soneone). Thats why I get Armour fron USA. Would rather do it officially here.
We are and very much appreciate the post , but we’d like to get it (NDT/T3) prescribed on the NHS, not be buying it on the internet. I even see people here left suffering with highly abnormal blood tests, trying to find out where to buy T4. But the comments were an aside on my part.
Also NHS don't look at antithyroid antibodies in blood... at least not in my experience;I only found out I'd got a lot by private blood test.. Infact no one had told me anything about them before I saw a reading in my private blood test. I think the NHS is missing out on a lot of "easy" good outcomrs by not opening up the "protocol". But maybe this would be opening themselves up to a lot of retrosprctive malpractice claims as the knowledge has been available for years.
Also NHS don't look at antithyroid antibodies in blood... at least not in my experience;
i feel quite lucky then ... turns out they've done my TPOab three times without me asking/knowing about it.
but i don't know why they did the second two... one might have been to recheck the original wasn't a mistake as it was so high.
they were then done again about 15yrs later, which might possibly have been triggered by an unexpectedly over range TSH .
I'd never though about your point re. retrospective malpractice due to info available for years.... i guess that could be playing a part in maintaining the staus quo.
Even 20 yrs ago, when i now discover it seemed easier to be prescribed T3 on the NHS and it was much cheaper than now, i wasn't told about an option of 'other' thyroid hormone treatment..... just told to look for 'other causes' of remaining symptoms on Levo. ) ie. in my head .
But they would probably just say there wasn't 'evidence it was better than levo' ., and 'evidence' is unfortunately different to 'knowledge' (and it can be manipulated to say what the authors/funders want it to)
I'm a bit late to this topic. There is some evidence that thyroxine (i.e. T4) increases the incidence of some cancers and death rates. This has implications for levothyroxine monotherapy as it usually involves higher fT4 levels. I plan to do a write up on this later this year so will hold off from any further comment as it is a vital topic that needs a careful and balanced presentation.
Background: The prescription of liothyronine (LT3) to treat hypothyroidism is increasing worldwide; however, the long-term safety of LT3 use has yet to be determined. Previous studies have suggested a possible association between LT3 use and breast cancer. The aim of this study was to examine the effects of LT3 use on cancer incidence and mortality.
Methods: Our sample included the full adult population of individuals living in Sweden with at least three purchases of thyroid hormone therapy between July 2005 and December 2017. Individual-level data on drug purchases were linked to registry data on cancer incidence and mortality. There were 575,461 individuals with at least three purchases, of which 11,147 had made at least three purchases of LT3, including combinations of levothyroxine (LT4) and LT3. Individuals were followed for a median follow-up time of 8.1 years. We applied Cox regression with a time-varying exposure variable, comparing LT3 users (individuals with at least three cumulative purchases of LT3) with LT4-only users (the rest). Outcomes included breast cancer incidence, any cancer incidence, all-cause mortality, any cancer mortality, and breast cancer mortality. We adjusted for age, sex, previous thyroid cancer, previous other cancer, use of antithyroid preparations, use of sex hormones, and dose in multivariate analyses.
Results: Multivariate analyses produced a hazard ratio of 0.93 (95% confidence interval [0.75–1.15]) for breast cancer incidence (only females), 0.97 (0.87–1.08) for any cancer incidence, 0.69 (0.61–0.77) for all-cause mortality, 0.78 (0.62–0.98) for any cancer mortality, and 0.91 (0.50–1.66) for breast cancer mortality (only females).
Conclusions: In this large, Swedish, long-term registry-based study, the use of LT3 did not lead to increased breast cancer incidence, any cancer incidence, all-cause mortality, any cancer mortality, or breast cancer mortality compared with LT4 use. Somewhat surprisingly, there was evidence of lower mortality in LT3 users in models adjusting for dose, potentially an artifact of underlying associations between dose and health status/diagnosis.
Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.
Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.
