Thiotépa

Thiotepa and its active metabolites (TEPA, monochlorotepa and thiotepa-mercapturate) are antineoplastics with alkylating action.
Indicated in the treatment of solid tumors, ovarian, breast and bladder cancer and in conditioning treatment before a transplantation of hematopoietic stem cells.
Administration by parenteral or intramuscular route in intervals of between 1 and 4 weeks or daily for 4 days.

Since the last update date we have not found published data on its excretion in breastmilk.

Its pharmacokinetic data (low molecular weight, low percentage of plasma protein binding, high liposolubility), makes it probable that it could pass to breastmilk in potentially significant quantities.

Pharmacokinetics show that after 3 elimination half-lives (T½) 87.5% of the drug is eliminated from the body; after 4 T½ it is 94%, after 5 T½, 96.9%, after 6 T½, 98.4% and after 7 T½ it is 99%. From 7 T½ the plasmatic concentrations of drug in the body are negligible. In general, a period of at least five half-lives can be considered a safe waiting period before breastfeeding again (Anderson 2016).

Taking the longest published T½ of all the active metabolites as a reference, 21 hours for TEPA (ASHP 2016 p426), these 5 T½ would correspond to 4 days. Due to major side effects, it would be advisable to wait 7 T½, which would correspond to 6 days. Meanwhile, express and discard milk from the breast regularly to maintain production.

When it is possible to do so, milk detections of each patient to determine the total elimination of the drug would be the best indicator to resume breastfeeding between two cycles of chemotherapy.

During breast cancer treatment, breastfeeding must be interrupted due to potentially serious side effects for the infant. Chemotherapy does not affect milk production during or after treatment. Abrupt weaning can be psychologically traumatic for both the mother and the infant (Pistilli 2013). If the mother wishes, the production of milk can be maintained by regularly expressing milk from the breast, being able to return to breastfeeding in the periods in which no significant traces of the drug remain in the milk (Anderson 2016) or at the end of the treatment (Pistilli 2013).

Some chemotherapeutic agents with an antibiotic effect can alter the composition of the microbiota (bacterial set or bacterial flora) of the milk and the concentration of some of its components (Urbaniak 2014). This possibly occurs temporarily with subsequent recovery, although no harmful effects are assumed or have been reported in breastfed infants.

Women undergoing chemotherapy during pregnancy have lower rates of breastfeeding due to difficulties in breastfeeding (Stopenski 2017), needing more support to achieve it.

Given the strong evidence that exists regarding the benefits of breastfeeding for the development of babies and the health of mothers, it is advisable to evaluate the risk-benefit of any maternal treatment, including chemotherapy, individually advising each mother who wishes to continue with breastfeeding (Koren 2013).