# CTC vs STI Tx Guide

The clearest difference is price: STI Tx Guide at Free against CTC's $3.99. STI Tx Guide also leads on in-app purchases (none vs 1) and iOS requirement (15.0 vs 17.6). CTC's advantage is review sentiment (56% vs 36%). On update cadence, ads and device support there is nothing between them.

STI Tx Guide is free to download; CTC costs $3.99 up front. CTC sells 1 one-off in-app purchase. STI Tx Guide asks for nothing beyond the download.

Both ship on a similar rhythm, roughly every 2 months. The most recent releases landed on September 13, 2026 and August 28, 2026 respectively.

## The numbers

| Metric | CTC | STI Tx Guide |
| --- | --- | --- |
| Price | $3.99 | **Free** |
| Rating | — | **[3.5 (36 ratings)](https://appshunter.io/ios/app/sti-tx-guide/id655206856/reviews)** |
| Number of ratings | — | **36** |
| Positive reviews | **55.6% of reviews** | 35.7% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 2 months | Every 2 months |
| Monetization | Paid | **Free** |
| Size | 2 MB | 36 MB |
| Requires iOS | 17.6 | **15.0** |
| Devices | **iPhone, iPad, Mac** | iPhone, iPod |
| Age rating | 17+ | 12+ |
| Developer | [Arpacore B.V.](https://appshunter.io/developer/1441928570) | [Centers For Disease Control and Prevention](https://appshunter.io/developer/439259253) |

## What reviewers say

### CTC

[App page](https://appshunter.io/ios/app/ctc-ae-plus/id349258523)

This medical reference app provides quick access to standardized adverse event criteria and grading scales for oncology research. It allows for efficient logging, tracking, and reporting of patient events, including performance scores and custom entries. Data is kept strictly on-device for privacy and compliance.

**Highlights:** CTCAE v4 and v5 reference, Performance score integration (Karnofsky, ECOG, Lansky), Advanced adverse event logger, Custom event creation, CSV data import/export, On-device data storage

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Adverse Event Logger | $3.99 | one-time |


### STI Tx Guide

[App page](https://appshunter.io/ios/app/sti-tx-guide/id655206856)

Provides healthcare professionals with up-to-date, evidence-based recommendations for the prevention, diagnosis, and treatment of sexually transmitted infections. Features include clinical care guidance, sexual history resources, and patient materials for effective patient management.

**Highlights:** STI prevention recommendations, Diagnosis guidance, Treatment protocols, Clinical care assistance, Sexual history resources, Patient management tools

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is CTC free?

CTC costs $3.99, and also offers in-app purchases.

### Is STI Tx Guide free?

STI Tx Guide is free to download, with no in-app purchases.

### Do CTC or STI Tx Guide have ads?

Neither CTC nor STI Tx Guide shows ads.

### Which is updated more often, CTC or STI Tx Guide?

CTC ships an update every 2 months, and STI Tx Guide every 2 months. Most recently, CTC was updated on September 13, 2026 and STI Tx Guide on August 28, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*