Stimulator, low electric field, tumor treatment: medical device reports filed with FDA

811 reports carry this product code, 2012–2026; 2 brands with a page.

Read first · FDA's statement on these data

Adverse event reports submitted to FDA do not undergo extensive validation or verification. Therefore, a causal relationship cannot be established between product and reactions listed in a report. While a suspected relationship may exist, it is not medically validated and should not be the sole source of information for clinical decision making or other assumptions about the safety or efficacy of a product. Additionally, it is important to remember that adverse event reports represent a small percentage of total usage numbers of a product. Common products may have a higher number of adverse events due to the higher total number of people using the product. openFDA, FDA

FDA adds: "Although MDRs are a valuable source of information, this passive surveillance system has limitations, including the potential submission of incomplete, inaccurate, untimely, unverified, or biased data. In addition, the incidence or prevalence of an event cannot be determined from this reporting system alone due to potential under-reporting of events and lack of information about frequency of device use." And: "MDR data alone cannot be used to establish rates of events, evaluate a change in event rates over time or compare event rates between devices. The number of reports cannot be interpreted or used in isolation to reach conclusions about the existence, severity, or frequency of problems associated with devices."

Do not rely on openFDA to make decisions regarding medical care. While we make every effort to ensure that data is accurate, you should assume all results are unvalidated.

Not medical advice. This site counts what was reported to FDA. Questions about a medicine or device belong with a pharmacist or clinician.

811
reports with this product code: 0% of all MAUDE reports; 245
reports, 12 months to August 2026: 237 in the 12 months before; 0.1%
classified as malfunction: 62.3% across all reports; 3.3%
classified as death, as reported: 0.9% across all reports

Product code NZK is FDA's classification for "Stimulator, low electric field, tumor treatment" (unknown panel), a class 3 device. 811 medical device reports carry this product code, 0% of the MAUDE database, from February 2012 to August 2026.

245 reports arrived in the 12 months to August 2026, close to the 237 of the 12 months before. FDA releases MAUDE data monthly; reports can arrive months after an event, so the newest months grow in later releases. The event types recorded are injury (94.7%), death (3.3%) and other (1.8%). 2 brand names with a page on this site carry this code; the brands table is ordered by report count for navigation only. FDA states that "MDR data alone cannot be used to establish rates of events, evaluate a change in event rates over time or compare event rates between devices. The number of reports cannot be interpreted or used in isolation to reach conclusions about the existence, severity, or frequency of problems associated with devices." It adds that the reporting system "has limitations, including the potential submission of incomplete, inaccurate, untimely, unverified, or biased data."

Brands with this product code

Brand	Reports	Latest 12 months	Classified as death	Classified as malfunction
Optune Gio	560	245	0.2%	0.2%
Optune	202	0	2%	0%

Ordered by report count for navigation only. FDA states that "MDR data alone cannot be used to establish rates of events, evaluate a change in event rates over time or compare event rates between devices. The number of reports cannot be interpreted or used in isolation to reach conclusions about the existence, severity, or frequency of problems associated with devices." It adds that the reporting system "has limitations, including the potential submission of incomplete, inaccurate, untimely, unverified, or biased data."

Reports by month, five years

FDA releases MAUDE data monthly; reports can arrive months after an event, so the newest months grow in later releases.

Event type and report source

Event type

Death3.3%27

Injury94.7%768

Malfunction0.1%1

Other1.8%15

Not given0%0

Who filed

Manufacturer report99.6%808

Voluntary report0.4%3

User facility report0%0

Distributor report0%0

Not given0%0

Grey bar: all 26,136,888 MAUDE reports.

Device problems coded

Device problem (FDA code)	Reports	Share
Insufficient device problem information	19	2.3%
Connection problema connection problem	1	0.1%
Device operates differently than expectedthe device behaved unexpectedly	1	0.1%
Device-device incompatibility	1	0.1%
Improper or incorrect procedure or method	1	0.1%
Inappropriate/inadequate shock/stimulation	1	0.1%
Material erosion	1	0.1%
Patient-device incompatibilitythe device did not suit the patient	1	0.1%

Questions about stimulator, low electric field, tumor treatment reports

What is product code NZK?

FDA's classification code for "Stimulator, low electric field, tumor treatment", class 3, reviewed by the unknown panel. Every device report carries the product code of the device involved.

How many reports carry this code?

811 reports through August 2026, 245 of them in the latest 12 months.

Which brands appear most often?

Optune Gio (560) and Optune (202). Widely used products collect more reports because more people use them.

Can the brands table be used to rank the devices?

No. FDA states that "MDR data alone cannot be used to establish rates of events, evaluate a change in event rates over time or compare event rates between devices. The number of reports cannot be interpreted or used in isolation to reach conclusions about the existence, severity, or frequency of problems associated with devices." It adds that the reporting system "has limitations, including the potential submission of incomplete, inaccurate, untimely, unverified, or biased data." Brands differ in how many are in use, how long they have been sold and how reports are collected.

Where this comes from. Counts are built from the openFDA Device Adverse Event (MAUDE) bulk export released 28 Sep 2026, which holds reports FDA received through 31 Aug 2026. Brand, generic and manufacturer names are as written on the reports; product code names come from FDA's device classification. No report narrative, lot number, patient detail or reporter identity is published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.

Drug data (FAERS) through 30 Jun 2026; device data (MAUDE) through 31 Aug 2026. Not medical advice.