APPENDICURE

Cancer Types & Subtypes

The most common appendiceal cancer subtypes patients are diagnosed with, plus the rare ones.

Adenocarcinoma

A cancer that begins in the glandular cells lining an organ. In the appendix, it’s the second most common type of cancer after neuroendocrine tumors, and it includes several subtypes (mucinous, colonic-type, signet ring, goblet cell).

Adenocarcinoid Tumor

An older term for goblet cell adenocarcinoma. These aggressive tumors have features of both adenocarcinoma and neuroendocrine tumors and are typically treated like mucinous adenocarcinoma.

Carcinoid Tumor

A slow-growing type of neuroendocrine tumor and the most common appendix cancer, making up about half of cases. Usually found at the tip of the appendix and often discovered incidentally after an appendectomy for appendicitis.

Colonic-Type Adenocarcinoma

An appendix cancer that looks and behaves like colon cancer under the microscope. Often grows near the base of the appendix and can mimic appendicitis at diagnosis.

Goblet Cell Adenocarcinoma (GCA)

A rare and aggressive cancer with features of both adenocarcinoma and neuroendocrine tumors. Previously called goblet cell carcinoid. GCA is considered high-grade and often requires more aggressive treatment than typical carcinoid tumors.

High-Grade Appendiceal Mucinous Neoplasm (HAMN)

A mucinous tumor of the appendix with high-grade cellular features but without invasive growth. More aggressive than LAMN and more likely to recur or spread.

High-Grade Mucinous Carcinoma Peritonei (HGMCP)

Previously called peritoneal mucinous adenocarcinoma (PMCA). Refers to the spread of mucin and invasive cancer cells throughout the abdominal cavity, most often originating from the appendix.

Low-Grade Appendiceal Mucinous Neoplasm (LAMN)

A slow-growing mucinous tumor confined to the appendix. While technically not cancer in the traditional sense, LAMN can rupture and spread mucin into the abdominal cavity, leading to pseudomyxoma peritonei.

Mucinous Adenocarcinoma

An appendix cancer that produces large amounts of mucin (a jelly-like substance). The tumor often ruptures and spreads mucin and cancer cells into the peritoneal cavity, leading to pseudomyxoma peritonei.

Mucocele

A swelling or pouch in the appendix filled with mucin. Mucoceles can be benign or cancerous and are usually removed surgically to determine which.

Neuroendocrine Tumor (NET)

A tumor that develops from hormone-producing cells. Most appendiceal NETs are small, slow-growing, and curable with surgery alone. Larger or higher-grade NETs may require more extensive treatment.

Paraganglioma

A rare, usually benign tumor that arises from nerve tissue. Extremely uncommon in the appendix.

Pseudomyxoma Peritonei (PMP)

A condition where mucin-producing tumor cells spread throughout the abdominal cavity, filling it with jelly-like mucus. Almost always originates from an appendiceal tumor. Categorized as low-grade (LGMCP) or high-grade (HGMCP).

Signet Ring Cell Carcinoma (SRCC)

A rare and aggressive appendix cancer where cells fill with mucin that pushes the nucleus to one side, creating a “signet ring” appearance under the microscope. Considered high-grade and typically requires aggressive treatment.

Pathology & Diagnosis

Terms you’ll see on biopsy results, pathology reports, and in conversations with your oncologist.

Benign

Non-cancerous. A benign growth doesn’t spread to other parts of the body.

Biopsy

A small sample of tissue removed and examined under a microscope to look for cancer cells and determine the type and grade.

Differentiation

How much cancer cells resemble normal cells. Well-differentiated cancers look more like normal tissue and often grow more slowly. Poorly differentiated cancers look very abnormal and tend to be more aggressive.

Grade

A measure of how abnormal cancer cells look under a microscope. Low-grade tumors look closer to normal and grow slowly. High-grade tumors look very abnormal and grow faster. Grade is different from stage.

Lymphovascular Invasion (LVI)

Cancer cells found inside small blood vessels or lymph vessels in the tumor area. LVI suggests a higher risk that cancer may have spread.

Malignant

Cancerous. A malignant tumor can grow into nearby tissue and spread to other parts of the body.

Margins

The edge of tissue removed during surgery. Clean (or negative) margins mean no cancer cells were found at the edges. Positive margins mean cancer cells were present at the edge, suggesting some cancer may have been left behind.

Metastasis

The spread of cancer from where it started to a distant part of the body. In appendix cancer, the most common site of spread is the peritoneum.

Mitotic Rate

A count of how many cells in a tumor are actively dividing, used to help determine grade. Higher mitotic rates usually indicate faster-growing tumors.

Perforation

A hole or rupture in the appendix wall. When an appendiceal tumor perforates, cancer cells and mucin can spill into the abdominal cavity, leading to peritoneal spread.

Peritoneal Carcinomatosis

Widespread cancer involving the peritoneum (the lining of the abdominal cavity). Common with advanced appendix cancer.

Stage

A measure of how far cancer has spread, usually expressed as Stage 1 through 4. Stage is based on tumor size, lymph node involvement, and whether cancer has spread to distant organs. Stage is different from grade.

Synchronous

Occurring at the same time. A synchronous tumor is one that exists alongside the primary cancer at the time of diagnosis.

Tumor Markers

Substances in the blood that can be elevated when cancer is present. Common ones for appendix cancer include CEA, CA 19-9, and CA-125. Tumor markers help monitor response to treatment and detect recurrence.

Anatomy

Parts of the body relevant to appendix cancer and its treatment.

Appendix

A small, finger-shaped pouch attached to the large intestine in the lower right side of the abdomen. Its function is not fully understood, but it may play a role in immune health.

Cecum

The first part of the large intestine, located in the lower right abdomen. The appendix attaches to the cecum.

Mesothelium

The thin layer of tissue that lines internal body cavities and covers organs. The peritoneum is part of the mesothelium.

Omentum

A fatty layer of tissue that hangs over the intestines and other abdominal organs. Often one of the first sites where appendix cancer spreads, and frequently removed during cytoreductive surgery.

Peritoneal Cavity

The space inside the abdomen bounded by the peritoneum. Contains the intestines, liver, spleen, and other organs.

Peritoneum

The membrane that lines the abdominal cavity and covers the abdominal organs. Common site for appendix cancer to spread.

Retroperitoneum

The space behind the peritoneum, containing the kidneys, pancreas, and major blood vessels. Distinct from the peritoneal cavity.

Imaging & Diagnostic Tests

The scans and lab tests used to diagnose, stage, and monitor appendix cancer.

CA-125

A blood test measuring a protein elevated in some cancers, including ovarian, peritoneal, and certain appendix cancers. Used to monitor treatment response and recurrence.

CA 19-9

A blood test measuring a protein elevated in some gastrointestinal cancers. Often used to track mucinous appendix cancer over time.

Carcinoembryonic Antigen (CEA)

A blood test that measures a protein commonly elevated in colorectal and appendix cancers. Used at diagnosis and to monitor treatment.

Colonoscopy

A procedure that uses a flexible tube with a camera to examine the inside of the colon and rectum. Can sometimes detect appendix tumors near the cecum.

Computed Tomography (CT Scan)

An imaging test that uses X-rays to create detailed cross-sectional images of the body. The most common scan for staging and monitoring appendix cancer.

Diagnostic Laparoscopy

A minimally invasive surgery where a small camera is inserted through tiny incisions to examine the abdomen directly. Often used to assess the extent of peritoneal disease before planning major surgery.

Magnetic Resonance Imaging (MRI)

An imaging test that uses magnets and radio waves to create detailed images of soft tissue. Sometimes used when CT scans are unclear, especially for mucinous tumors.

Positron Emission Tomography (PET Scan)

An imaging test that uses a small amount of radioactive sugar to highlight metabolically active areas, often cancer. Less useful for low-grade mucinous appendix cancers, more useful for high-grade or recurrent disease.

Signatera

A blood test that detects circulating tumor DNA (ctDNA) specific to a patient’s tumor, used to monitor for recurrence. Requires a tissue sample to create a personalized test.

Tumor Marker Panel

A combination of blood tests (typically CEA, CA 19-9, and CA-125) drawn together to track appendix cancer over time.

Molecular & Genetic Testing

Increasingly important terms patients will see on tumor profiling reports from companies like Caris, Foundation Medicine, Tempus, and Natera.

BRAF

A gene that, when mutated, can drive cancer growth. BRAF mutations are uncommon in appendix cancer but worth testing for because targeted therapies exist.

CDK4/6 Inhibitor

A class of targeted drugs (like palbociclib) that blocks proteins cancer cells need to divide. Showing promise in mucinous appendix cancers with GNAS mutations.

Circulating Tumor DNA (ctDNA)

Small fragments of cancer DNA that float in the bloodstream. Detecting ctDNA can signal active cancer or recurrence even when imaging looks clear.

Foundation Medicine

A company that performs comprehensive genomic profiling on tumor tissue or blood, identifying mutations that may guide treatment decisions.

GNAS

A gene frequently mutated in mucinous appendiceal tumors. GNAS mutations are an appendix-specific finding rarely seen in colon cancer, which is why treating appendix cancer like colon cancer can miss important treatment options.

KRAS

A commonly mutated gene in appendix and colon cancers. KRAS mutations affect how cells grow and divide, and they influence which targeted treatments may or may not work.

Liquid Biopsy

A blood test that detects cancer DNA or other markers without needing a tissue sample. Less invasive than a traditional biopsy and useful when tumor tissue is hard to access.

Microsatellite Instability (MSI)

A pattern of mutations caused by faulty DNA repair. MSI-high tumors often respond well to immunotherapy. Most appendix cancers are MSI-stable (MSS), but testing identifies the patients who could benefit.

Mismatch Repair (MMR)

A system cells use to fix DNA errors. When this system is broken (deficient mismatch repair, or dMMR), tumors accumulate many mutations and may respond to immunotherapy.

Natera

A company offering molecular testing including the Signatera ctDNA test for monitoring recurrence and the Altera tumor profiling test.

Next-Generation Sequencing (NGS)

Advanced lab technology that reads many genes at once to find mutations that might guide treatment. The basis of most modern tumor profiling tests.

PIK3CA

A gene sometimes mutated in appendix cancer that affects cell growth pathways. Several targeted therapies are in development for PIK3CA-mutated tumors.

Tempus

A company that performs tumor genomic profiling, similar to Foundation Medicine and Caris.

TP53

A tumor suppressor gene often called the “guardian of the genome.” Mutations in TP53 are common in higher-grade appendix cancers and generally indicate more aggressive disease.

Tumor Mutational Burden (TMB)

The number of mutations in a tumor’s DNA. High TMB tumors may respond better to immunotherapy. Most appendix cancers have low TMB.

Surgery & Procedures

Operations and procedures used to treat appendix cancer.

Appendectomy

Removal of the appendix. Often sufficient treatment for small, low-risk neuroendocrine tumors found incidentally.

Colostomy

A surgically created opening in the abdominal wall that allows stool to exit the body, bypassing part of the colon. Can be temporary or permanent depending on the situation.

Completeness of Cytoreduction Score (CC Score)

A rating from 0 (no visible tumor remaining) to 3 (large amounts of tumor remaining) of how thoroughly cytoreductive surgery removed visible disease. A CC-0 or CC-1 result correlates with the best outcomes.

Cytoreductive Surgery (CRS)

An extensive operation to remove all visible tumor and mucin from the abdominal cavity. Often combined with HIPEC. Typically performed at specialized centers and can take 8 to 12 hours or longer.

Debulking

An older term for surgery that removes as much tumor as possible. Cytoreductive surgery is the modern, more aggressive version.

Hemicolectomy

Surgery to remove part of the colon along with the appendix. Right hemicolectomy (removing the right side of the colon) is the standard surgery for many appendix cancers, particularly higher-grade tumors or those at the base of the appendix.

Hyperthermic Intraperitoneal Chemotherapy (HIPEC)

A treatment where heated chemotherapy solution is circulated throughout the abdominal cavity during surgery to kill microscopic cancer cells. Usually performed immediately after cytoreductive surgery.

Ileostomy

A surgically created opening in the abdominal wall that allows waste from the small intestine to exit the body. May be temporary (often used to protect a healing surgical connection) or permanent.

Laparoscopy

Minimally invasive surgery performed through small incisions using a camera and specialized instruments.

Laparotomy

Traditional “open” abdominal surgery using a larger incision. Required for cytoreductive surgery and most major appendix cancer procedures.

Omentectomy

Removal of the omentum, a fatty layer covering the intestines. Standard part of cytoreductive surgery because the omentum is a common site of cancer spread.

Peritonectomy

Surgical removal of part of the peritoneum (the lining of the abdomen) when cancer has spread to it. Frequently performed during cytoreductive surgery.

Pressurized Intraperitoneal Aerosolized Chemotherapy (PIPAC)

A laparoscopic procedure that delivers chemotherapy as a pressurized mist sprayed into the abdominal cavity. Less invasive than HIPEC and can be repeated, often used for palliation or for patients who can’t undergo CRS.

Right Hemicolectomy

Removal of the appendix, cecum, and the right portion of the colon, sometimes with nearby lymph nodes. The most common definitive surgery for higher-risk appendiceal tumors.

Chemotherapy & Targeted Therapy

Drugs used to treat appendix cancer, by category. Inclusion here is not a recommendation; treatment decisions are individual.

5-Fluorouracil (5-FU)

A chemotherapy drug given through an IV that has been used for decades to treat gastrointestinal cancers. Part of most appendix cancer chemotherapy regimens.

Adjuvant Therapy

Treatment given after the main treatment (usually surgery) to reduce the chance of cancer coming back.

Bevacizumab (Avastin)

A targeted therapy that blocks blood vessel growth in tumors. Sometimes added to chemotherapy for appendix cancer with peritoneal spread.

Capecitabine (Xeloda)

An oral chemotherapy pill that converts to 5-FU in the body. Often used as a more convenient alternative to IV 5-FU, especially for maintenance therapy.

FOLFIRI

A chemotherapy regimen combining 5-FU, leucovorin, and irinotecan. Used for some appendix cancers, often after FOLFOX or when FOLFOX is not tolerated.

FOLFOX

A chemotherapy regimen combining 5-FU, leucovorin, and oxaliplatin. One of the most common regimens used for appendix cancer. Oxaliplatin commonly causes neuropathy.

Immunotherapy

Treatments that help the immune system recognize and attack cancer. Most effective in tumors with high mutation burden or MSI-high status. Less commonly effective in appendix cancer but tested in select cases.

Irinotecan

A chemotherapy drug used in FOLFIRI and other regimens. Can cause significant gastrointestinal side effects.

Leucovorin

A vitamin-related drug given with 5-FU to enhance its effectiveness. Sometimes called folinic acid.

Maintenance Therapy

A less intensive treatment given after an initial course of stronger therapy, designed to keep cancer stable for as long as possible.

Neoadjuvant Therapy

Treatment given before the main treatment (usually surgery), often to shrink the tumor and improve surgical outcomes.

Oxaliplatin

A chemotherapy drug used in FOLFOX. Known for causing cumulative neuropathy, which is why FOLFOX is often switched to capecitabine after several cycles.

Palbociclib (Ibrance)

A CDK4/6 inhibitor approved for certain breast cancers and being studied in mucinous appendiceal tumors with GNAS mutations.

Pembrolizumab (Keytruda)

An immunotherapy drug (PD-1 inhibitor) used in cancers with MSI-high or dMMR status. Occasionally relevant for appendix cancers with those biomarkers.

Systemic Chemotherapy

Chemotherapy delivered through the bloodstream (IV or oral) to reach cancer cells anywhere in the body. Different from regional treatments like HIPEC or PIPAC.

Targeted Therapy

Treatments designed to attack specific molecules involved in cancer growth. Examples include bevacizumab and palbociclib.

Radiation & Other Treatments

External Beam Radiation

Radiation delivered from a machine outside the body, aimed at the tumor. Less commonly used for appendix cancer than for many other cancer types.

Palliative Care

Specialized medical care focused on relieving symptoms, managing pain, and improving quality of life. Available at any stage of illness, not just end of life. Can be provided alongside cancer treatment.

Radiation Therapy

The use of high-energy radiation (X-rays, gamma rays, or particles) to kill cancer cells or slow their growth.

Clinical Trials & Research

Terms patients encounter when exploring clinical trial options.

Arm (Trial Arm)

One of the groups in a clinical trial. A trial might have a “treatment arm” receiving the new therapy and a “control arm” receiving standard treatment.

Biomarker

A measurable substance (often a protein, gene mutation, or genetic feature) in blood or tissue that gives information about disease, treatment response, or prognosis.

ClinicalTrials.gov

The U.S. government database of clinical trials worldwide. Each trial has an NCT identifier.

Cohort

A group of patients in a clinical trial sharing certain characteristics (such as cancer type or treatment received).

Eligibility Criteria

The requirements a patient must meet to join a clinical trial, including diagnosis, prior treatments, and overall health.

Endpoint

What a clinical trial is measuring to determine whether a treatment worked. Examples include overall survival, progression-free survival, and response rate.

Institutional Review Board (IRB)

A committee that reviews and approves research studies to make sure they are ethical and protect patient safety.

NCT Number

A unique identifier given to every clinical trial registered on ClinicalTrials.gov, formatted as NCT followed by 8 digits.

Phase 1 Trial

An early-stage trial focused on safety and dosing in a small group of patients.

Phase 2 Trial

A mid-stage trial that tests whether a treatment works in a larger group, while continuing to assess safety.

Phase 3 Trial

A large trial comparing the new treatment against the current standard of care to confirm effectiveness.

Randomization

The process of randomly assigning trial participants to different treatment groups to reduce bias.

Standard of Care

The currently accepted treatment for a given condition, based on best available evidence.

Disease Course & Outcomes

Words used to describe how cancer behaves over time and how patients respond to treatment.

Disease-Free Survival

The length of time after treatment a patient lives without any sign of cancer.

Local Recurrence

Cancer returning in or near the original site after treatment.

No Evidence of Disease (NED)

A status meaning current scans, blood tests, and exams show no signs of active cancer. Different from “cured,” but a positive milestone in cancer care.

Overall Survival (OS)

The length of time from diagnosis or treatment start that patients are still alive. A primary outcome measured in clinical trials.

Peritoneal Cancer Index (PCI)

A score from 0 to 39 that quantifies the amount and distribution of cancer in the abdominal cavity. Higher scores mean more extensive disease. Used to guide surgical planning.

Progression

Cancer growing, spreading, or worsening despite treatment.

Progression-Free Survival (PFS)

The length of time during and after treatment that cancer does not grow or spread.

Recurrence

Cancer returning after a period of being undetectable. Can occur in the original location (local) or elsewhere in the body (distant).

Remission

A reduction or disappearance of cancer signs and symptoms. Partial remission means cancer has decreased; complete remission means no detectable cancer.

Response Rate

The percentage of patients whose cancer shrinks or disappears in response to a treatment.

Stable Disease

Cancer that is neither growing nor shrinking. For some appendix cancers, stable disease is considered a treatment success.

Survivorship

The phase of cancer care that begins at diagnosis and continues throughout life, including treatment, recovery, and follow-up care.

Side Effects & Supportive Care

Common physical effects of cancer or its treatment, and the care that helps manage them.

Anemia

A low red blood cell count that causes fatigue and weakness. Common during chemotherapy.

Cachexia

Severe weight loss and muscle wasting from advanced cancer. Different from typical weight loss and requires specific nutritional support.

Hand-Foot Syndrome

Redness, peeling, pain, or swelling of the hands and feet, a common side effect of capecitabine and some other chemotherapies. Managed with moisturizers and dose adjustments.

Neuropathy

Nerve damage causing tingling, numbness, pain, or weakness, usually starting in the hands and feet. A common side effect of oxaliplatin and some other chemotherapies. Can be temporary or permanent.

Neutropenia

A low count of neutrophils, a type of white blood cell that fights infection. A common side effect of chemotherapy that increases infection risk.

Port (Port-a-Cath)

A small device implanted under the skin to provide easy access for IV chemotherapy and blood draws, avoiding repeated needle sticks.

Stoma

The opening in the abdomen created during ostomy surgery (colostomy or ileostomy) through which waste exits the body.

Thrombocytopenia

A low platelet count that increases bleeding risk. A common side effect of chemotherapy.

Total Parenteral Nutrition (TPN)

Complete nutrition delivered through an IV when a patient can’t eat or absorb food normally. Sometimes needed after major abdominal surgery.