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Thymus therapy for cancer

Clinical bottom line: There is a lack of quality evidence for thymus therapy as an adjuvant to orthodox cancer treatment. Preliminary evidence suggests there may be some benefits of thymus therapy on T-cell function, but this needs further investigation. Evidence for clinically relevant outcomes such as survival rate and time is contradictory, and needs further investigation.


Thymus therapy involves administering preparations of thymus extract (usually bovine) to patients orally, intramuscularly or intravenously as an adjuvant to orthodox treatment. It is thought that this boosts immune function since the thymus is thought to be an important organ for the development of cell-mediated immunological defence. Thymic hormones are involved in the maturation of T lymphocytes. Proponents of this therapy believe that cancer and/or its orthodox treatments are associated with immunosuppression, and hence diminished defence against malignant growth.

Systematic review

Ernst E. Thymus therapy for cancer? A criteria-based, systematic review. European Journal of Cancer 1997; 33(4):531-535.

Date review completed: 1996

Number of trials included: 13 (1 double-blind)

Control group: usual treatment alone

Main outcomes: immunological variables, survival time, survival rate, etc.

Inclusion criteria were randomised clinical trials of thymus therapy for cancer.

Reviewers provided descriptive summary of included trials, methodologies and main findings. A brief search on PubMed revealed no additional trials.

Findings

Thirteen trials were included. Methodological quality was generally poor, and only one trial was double-blind. Most trials were small, and therefore lacked adequate power. Dosing regimens, thymus preparation and length of intervention varied.

Double-blind trials

One trial of 67 patients who had received chemotherapy for breast cancer compared daily doses of oral thymus with placebo. There was significant improvement in T4/T8 quotient and in patient reports of well-being. Survival and recurrence rates were not reported.

Single-blind

One trial of 36 patients with breast or colorectal cancer compared two different thymus preparations with a vitamin B6 complex placebo. Thymus appeared to be associated with improvement in T-cell function, but reviewers noted that treatment details and statistical methodology details were not adequately described. Survival and recurrence rates were not reported.

Open trials

Eleven trials were included. It is difficult to make sense of this information due to the inherent bias in design, small sample sizes and outcomes of questionable relevance. Nine of eleven trials reported some benefit of thymus on at least one measure. Trials looking at outcomes of clinical relevance, e.g. survival time and survival rates are summarised in the Table. The table does not contain this information when trialists/reviewers did not report on size of effect because in these circumstances clinical relevance can not be assessed.

Table: Summary of clinically relevant outcomes for open trials of thymus therapy for cancer

Outcome Type of cancer Number of trials Number of patients Thymus Placebo Conclusion
6 month mortality Inoperable lung cancers 1 50 52% 28% Poorer survival with thymus
Complete or partial remission Advanced colorectal carcinoma 1 241 30% 18% Higher remission rates with thymus
Complete response rate Non-Hodgkin's lymphoma 1 134 59% 42% Higher complete response rates with thymus (4 year survival rates show no significant benefit)

Adverse effects

Reviewers did not report on adverse effects as reported in the trials, but note that adverse effects of thymus therapy are well recognised.

Further reading


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