Scarlett Arthur
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Is anyone able to help with the below please? I am having a complete blank with the data.

To determine the role of the pharmacokinetics of tamoxifen in the treatment of metastatic breast cancer, the steady-state plasma concentration of the active metabolite of tamoxifen, endoxifen, was monitored in 217 patients.

All the patients were white premenopausal (ages 28-52) UK females

All had histologically or cytologically diagnosed breast cancer with oestrogen positive tumours.

All patients received the same dose of tamoxifen and were treated for 12 months.

At 12 months the clinical benefits of the treatment were assessed. The following clinical outcomes were measured (Table 1):
- Complete response (CR) (tumour absent)
- Partial response (PR) (significant reduction of tumour size)
- Stable disease (SD) (no change)
- Progressive disease (PRD) (increased tumour size and/or spread).

a) What do these data suggest? Justify your answer.

b) What may underlie the differences in the levels plasma concentration of endoxifen among the patients? Justify your answer.

c) On the basis of the finding of this study and taking into account all the effects of tamoxifen, propose a strategy to increase the benefit of tamoxifen treatment to all patients.

Should I be making another graph to analyse the data or literally just look at it?

Image
Last edited by Scarlett Arthur; 1 month ago
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Jpw1097
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(Original post by Scarlett Arthur)
Is anyone able to help with the below please? I am having a complete blank with the data.

To determine the role of the pharmacokinetics of tamoxifen in the treatment of metastatic breast cancer, the steady-state plasma concentration of the active metabolite of tamoxifen, endoxifen, was monitored in 217 patients.

All the patients were white premenopausal (ages 28-52) UK females

All had histologically or cytologically diagnosed breast cancer with oestrogen positive tumours.

All patients received the same dose of tamoxifen and were treated for 12 months.

At 12 months the clinical benefits of the treatment were assessed. The following clinical outcomes were measured (Table 1):
- Complete response (CR) (tumour absent)
- Partial response (PR) (significant reduction of tumour size)
- Stable disease (SD) (no change)
- Progressive disease (PRD) (increased tumour size and/or spread).

a) What do these data suggest? Justify your answer.

b) What may underlie the differences in the levels plasma concentration of endoxifen among the patients? Justify your answer.

c) On the basis of the finding of this study and taking into account all the effects of tamoxifen, propose a strategy to increase the benefit of tamoxifen treatment to all patients.

Should I be making another graph to analyse the data or literally just look at it?

Image
First look at the plasma endoxifen (tamoxifen metabolite) across the groups. Endoxifen levels are highest in type X, lower in type Y and lowest in type Z. I'm not sure why type X and type Y have been separated as it looks as though they should be one group, their IQRs overlap and therefore they are not significantly different.

Next look at the baseline characteristics across the groups - they are similar and so any observed effect is unlikely to be due to differences in baseline characteristics (e.g. demographics).

I would convert the raw numbers in the table into percentages, that way you can compare across groups. I am not going to do this for you but if you do this, you will find that in type X and type Y, there are much higher rates of complete and partial response compared to type Z. In type Z, there are much higher rates of stable and progressive disease compared to type X and Y. Given that type X and Y have higher plasma levels of endoxifen compared to type Z, you could infer that higher levels of endoxifen are correlated with better outcomes. This makes sense given that tamoxifen is used to treat breast cancer.

In terms of why might the plasma concentrations of endoxifen be different, this is due to pharmacokinetics - absorption, distribution, metabolism and excretion (ADME). Perhaps you could come up with some examples of how these differences may occur.

Question C is linked to the previous. If you can come up with examples of how differences in pharmacokinetics differ between patients, you can coome up with potential ways to modify their pharmacokinetics.

For example, suppose an enzyme metabolises the active metabolite of tamoxifen (endoxifen), you could potentially use a drug that inhibits that enzyme to raise concentrations of endoxifen.
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Scarlett Arthur
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thank you for taking the time to be so helpful
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