Surgery, if feasible, is the only curative therapy. If the tumor has metastasized (most commonly, to the liver) and is considered incurable, there are some promising treatment modalities, such as radiolabeled octreotide (e.g. Lutetium (Lu) DOTA-octreotate) or the radiopharmaceutical 131I-mIBG (meta iodo benzyl guanidine) for arresting the growth of the tumors and prolonging survival in patients with liver metastases, though these are currently experimental.

Chemotherapy is of little benefit and is generally not indicated. Octreotide or Lanreotide (somatostatin analogues) may decrease the secretory activity of the carcinoid, and may also have an anti-proliferative effect. Interferon treatment is also effective, and usually combined with somatostatin analogues.

As the metastatic potential of a coincidental carcinoid is probably low, the current recommendation is for follow up in 3 months with CT or MRI, labs for tumor markers such as serotonin, and a history and physical, with annual physicals thereafter.

In general, treatment for PanNET encompasses the same array of options as other neuroendocrine tumors, as discussed in that main article. However, there are some specific differences, which are discussed here.

In functioning PanNETs, octreotide is usually recommended prior to biopsy or surgery but is generally avoided in insulinomas to avoid profound hypoglycemia.

PanNETs in MEN1 are often multiple, and thus require different treatment and surveillance strategies.

Some PanNETs are more responsive to chemotherapy than are gastroenteric carcinoid tumors. Several agents have shown activity. In well differentiated PanNETs, chemotherapy is generally reserved for when there are no other treatment options. Combinations of several medicines have been used, such as doxorubicin with streptozocin and fluorouracil (5-FU) and capecitabine with temozolomide. Although marginally effective in well-differentiated PETs, cisplatin with etoposide has some activity in poorly differentiated neuroendocrine cancers (PDNECs), particularly if the PDNEC has an extremely high Ki-67 score of over 50%.

Several targeted therapy agents have been approved in PanNETs by the FDA based on improved progression-free survival (PFS):

- everolimus (Afinitor) is labeled for treatment of progressive neuroendocrine tumors of pancreatic origin in patients with unresectable, locally advanced or metastatic disease. The safety and effectiveness of everolimus in carcinoid tumors have not been established.

- sunitinib (Sutent) is labeled for treatment of progressive, well-differentiated pancreatic neuroendocrine tumors in patients with unresectable locally advanced or metastatic disease. Sutent also has approval from the European Commission for the treatment of 'unresectable or metastatic, well-differentiated pancreatic neuroendocrine tumors with disease progression in adults'. A phase III study of sunitinib treatment in well differentiated pNET that had worsened within the past 12 months (either advanced or metastatic disease) showed that sunitinib treatment improved progression-free survival (11.4 months vs. 5.5 months), overall survival, and the objective response rate (9.3% vs. 0.0%) when compared with placebo.

The main treatment modalities are surgery, embolization and radiotherapy.

Even if the tumor has advanced and metastasized, making curative surgery infeasible, surgery often has a role in neuroendocrine cancers for palliation of symptoms and possibly increased lifespan.

Cholecystectomy is recommended if there is a consideration of long-term treatment with somatostatin analogs.

In secretory tumors, somatostatin analogs given subcutaneously or intramuscularly alleviate symptoms by blocking hormone release. A consensus review has reported on the use of somatostatin analogs for GEP-NETs.

These medications may also anatomically stabilize or shrink tumors, as suggested by the PROMID study (Placebo-controlled prospective randomized study on the antiproliferative efficacy of Octreotide LAR in patients with metastatic neuroendocrine MIDgut tumors): at least in this subset of NETs, average tumor stabilization was 14.3 months compared to 6 months for placebo.

The CLARINET study (a randomized, double-blind, placebo-controlled study on the antiproliferative effects of lanreotide in patients with enteropancreatic neuroendocrine tumors) further demonstrated the antiproliferative potential of lanreotide, a somatostatin analog and recently approved FDA treatment for GEP-NETS. In this study, lanreotide showed a statistically significant improvement in progression-free survival, meeting its primary endpoint. The disease in sixty five percent of patients treated with lanreotide in the study had not progressed or caused death at 96 weeks, the same was true of 33% of patients on placebo. This represented a 53% reduction in risk of disease progression or death with lanreotide based on a hazard ratio of .47.

Lanreotide is the first and only FDA approved antitumor therapy demonstrating a statistically significant progression-free survival benefit in a combined population of patients with GEP-NETS.

Other medications that block particular secretory effects can sometimes relieve symptoms.

Radiotherapy alone is reserved only for small lesions not appropriate for either surgery or chemotherapy. Both photon and proton radiotherapy have been used effectively to treat esthesioneuroblastoma. Proton radiotherapy has recently been shown to be effective in a 10-person study with Kadish C tumors, while delivering less toxicity to the nervous system.

Chemotherapy is used in a multimodality treatment plan generally for more advanced, unresectable or reoccurring tumors. Cyclophosphamide, vincristine and doxorubicin have been used as neoadjuvant chemotherapy drugs for grade C esthesioneuroblastoma before surgical resection, producing fair outcomes. Cisplatin and etoposide are often used to treat esthesioneuroblastoma as neoadjuvants or adjuvants with radiotherapy or surgery. Study results are promising. In advanced stage esthesioneuroblastoma in pediatric patients, where surgery is no longer possible, aggressive chemotherapy and radiotherapy has resulted in some tumor control and long term survival.

Surgery is the mainstay of treatment for clinically localized disease. In feasible cases, a partial cystectomy with "en-bloc" resection of the median umbilical ligament and umbilicus can achieve good results. In progressed stages, radiotherapy seems not to lead to sufficient response rates. However, chemotherapy regimes containing 5-FU (and Cisplatin) have been described to be useful in these cases. In recent years, targeted therapies have been demonstrated to be useful in reports of single cases. These agents included Sunitinib, Gefitinib, Bevacizumab and Cetuximab.

Because LCLC-RP is so rare, no clinical trials have ever been conducted that specifically address treatment of this lung cancer variant. Because LCLC-RP is considered a form of non-small cell lung carcinoma (NSCLC), most physicians adhere to published NSCLC treatment guidelines in rhabdoid carcinoma cases. When possible, radical surgical resection with curative intent is the primary treatment of choice in early stage NSCLC's, and can be administered with or without adjuvant, neoadjuvant, or palliative chemotherapy and/or radiotherapy, depending on the disease stage and performance status of the individual patient.

In numerous clinical trials conducted in NSCLC, several different platinum-based chemotherapy regimens have been shown to be more-or-less equally effective. LCLC's, as a subtype of NSCLC, have traditionally been included in many of these clinical trials, and have been treated like other NSCLC's. More recent trials, however, have shown that some newer agents may have particular effectiveness in prolonging survival of LCLC patients. Pemetrexed, in particular, has shown significant reduction in the hazard ratio for death when used in patients with LCLC. Taxane-based (paclitaxel, docetaxel) chemotherapy was shown to induce a complete and sustained response in a liver metastasis in a case of LCC-RP. A later-appearing metastasis within mediastinal lymph nodes in the same case also showed a durable response to a taxane alone.

There have also been reports of rhabdoid carcinomas expressing vascular endothelial growth factor (VEGF), suggesting that targeted molecular therapy with VEGF blocking monoclonal antibodies such as bevacizumab may be active in these variants. However, evidence suggests that caution must be used when treating a cavitated rhabdoid tumor, one that contains significant components of squamous cell differentiation, or large tumors with containing major blood vessels, due to the potential high risk of life-threatening pulmonary hemorrhage.

A recent study reported a case wherein 2 courses of adjuvant therapy with cisplatin and paclitaxel, followed by oral gefitinib, were used after complete resection. The patient had had no recurrence 34 months later.

As large-volume LCLC-RP may show significant central necrosis and cavitation, prudence dictates that oncologists use extreme caution if contemplating the therapeutic use of bevacizumab, other anti-VEGF compounds, or anti-angiogenesis agents in general, which have been associated with a greatly increased risk of severe hemorrhage and hemoptysis that may be quickly fatal in cavatated pulmonary squamous cell carcinomas. Similar elevated risks have also been noted in tumors located near, or containing, large blood vessels.,

Wide, radical, complete surgical excision is the treatment of choice, with free surgical margins to achieve the best outcome and lowest chance of recurrence. Radiation is only used for palliation. In general, there is a good prognosis, although approximately 50% of patients die from disease within 3–10 years of presentation.

Surgical resection of the tumor is the treatment of first choice, either by open laparotomy or laparoscopy. Given the complexity of perioperative management, and the potential for catastrophic intra and postoperative complications, such surgery should be performed only at centers experienced in the management of this disorder. In addition to the surgical expertise that such centers can provide, they will also have the necessary endocrine and anesthesia resources. It may also be necessary to carry out adrenalectomy, a complete surgical removal of the affected adrenal gland(s).

Either surgical option requires prior treatment with the non-specific and irreversible alpha adrenoceptor blocker phenoxybenzamine or a short acting alpha antagonist (e.g. prazosin, terazosin, or doxazosin). Doing so permits the surgery to proceed while minimizing the likelihood of severe intraoperative hypertension (as might occur when the tumor is manipulated). Some authorities would recommend that a combined alpha/beta blocker such as labetalol also be given in order to slow the heart rate. Regardless, a nonselective beta-adrenergic receptor blocker such as propranolol must never be used in the presence of a pheochromocytoma. The mechanism for β-adrenoceptor blocker-associated adverse events is generally ascribed to inhibition of β2-adrenoceptor-mediated vasodilatation, leaving α1-adrenoceptor-mediated vasoconstrictor responses to catecholamines unopposed and, thus, severe and potentially refractory hypertension. However some clinical guidelines permit beta-1 blockade use together with alpha blockers during surgery for control of tachycardia.

The patient with pheochromocytoma is invariably volume depleted. In other words, the chronically elevated adrenergic state characteristic of an untreated pheochromocytoma leads to near-total inhibition of renin-angiotensin activity, resulting in excessive fluid loss in the urine and thus reduced blood volume. Hence, once the pheochromocytoma has been resected, thereby removing the major source of circulating catecholamines, a situation arises where there is both very low sympathetic activity and volume depletion. This can result in profound hypotension. Therefore, it is usually advised to "salt load" pheochromocytoma patients before their surgery. This may consist of simple interventions such as consumption of high salt food pre-operatively, direct salt replacement or through the administration of intravenous saline solution.

In ES-SCLC, combination chemotherapy is the standard of care, with radiotherapy added only to palliate symptoms such as dyspnea, pain from liver or bone metastases, or for treatment of brain metastases, which, in small-cell lung carcinoma, typically have a rapid, if temporary, response to whole brain radiotherapy.

Combination chemotherapy consists of a wide variety of agents, including cisplatin, cyclophosphamide, vincristine and carboplatin. Response rates are high even in extensive disease, with between 15% and 30% of subjects having a complete response to combination chemotherapy, and the vast majority having at least some objective response. Responses in ES-SCLC are often of short duration, however.

If complete response to chemotherapy occurs in a subject with SCLC, then prophylactic cranial irradiation (PCI) is often used in an attempt to prevent the emergence of brain metastases. Although this treatment is often effective, it can cause hair loss and fatigue. Prospective randomized trials with almost two years follow-up have not shown neurocognitive ill-effects. Meta-analyses of randomized trials confirm that PCI provides significant survival benefits.

Small carcinoids (<2 cm) without features of malignancy may be treated by appendectomy if complete removal is possible. Other carcinoids and adenocarcinomas may require right hemicolectomy. Note: the term "carcinoids" is outdated: these tumors are now more accurately called "neuroendocrine tumors." For more information, see "appendiceal neuroendocrine tumors."

Pseudomyxoma peritonei treatment includes cytoreductive surgery which includes the removal of visible tumor and affected essential organs within the abdomen and pelvis. The peritoneal cavity is infused with heated chemotherapy known as HIPEC in an attempt to eradicate residual disease. The surgery may or may not be preceded or followed with intravenous chemotherapy or HIPEC.

Radiotherapy is commonly used to treat Merkel-cell cancers. The radiotherapy fields used are usually very large so as to cover sufficient areas of skin. This is necessary because of MCC's aggressive local and regional metastatic behavior.

Adjuvant radiotherapy has been shown to be effective in reducing the rates of recurrence and in increasing the survival of patients with MCC. Patients who present with no distant metastases and a negative sentinel lymph node biopsy have a very good prognosis when treated with both surgery and radiotherapy (approximately 90% survival rate at five years).

Metastatic MCC may respond to treatment with chemotherapy and/or radiation, but current multimodal therapies are usually not curative. Intensive treatment can be effective in shrinking the tumor and improving operability when tumors are too large to be removed or located in a place where removal would be difficult or dangerous, or in palliation of signs and symptoms caused by metastatic tumors.

Treatment for FAP depends on the genotype. Most individuals with the APC mutation will develop colon cancer by the age of 40, although the less-common attenuated version typically manifests later in life (40–70). Accordingly, in many cases, prophylactic surgery may be recommended before the age of 25, or upon detection if actively monitored. There are several surgical options that involve the removal of either the colon or both the colon and rectum.

- Rectum involved: the rectum and part or all of the colon are removed. The patient may require an ileostomy (permanent stoma where stool goes into a bag on the abdomen) or have an ileo-anal pouch reconstruction. The decision to remove the rectum depends on the number of polyps in the rectum as well as the family history. If the rectum has few polyps, the colon is partly or fully removed and the small bowel (ileum) can be directly connected to the rectum instead (ileorectal anastomosis).

- Rectum not involved: the portion of the colon manifesting polyps can be removed and the ends 'rejoined' (partial colectomy), a surgery that has a substantial healing time, but leaves quality of life largely intact.

Prophylactic colectomy is indicated if more than a hundred polyps are present, if there are severely dysplastic polyps, or if multiple polyps larger than 1 cm are present.

Treatment for the two milder forms of FAP may be substantially different from the more usual variant, as the number of polyps are far fewer, allowing more options.

Various medications are being investigated for slowing malignant degeneration of polyps, most prominently the non-steroidal anti-inflammatory drugs (NSAIDs). NSAIDS have been shown to significantly decrease the number of polyps but do not usually alter management since there are still too many polyps to be followed and treated endoscopically.

In cases of LS-SCLC, combination chemotherapy (often including cyclophosphamide, cisplatinum, doxorubicin, etoposide, vincristine and/or paclitaxel) is administered together with concurrent chest radiotherapy (RT).

Chest RT has been shown to improve survival in LS-SCLC.

Exceptionally high objective initial response rates (RR) of between 60% and 90% are seen in LS-SCLC using chemotherapy alone, with between 45% and 75% of individuals showing a "complete response" (CR), which is defined as the disappearance of all radiological and clinical signs of tumor. However, relapse rate remains high, and median survival is only 18 to 24 months.

Because SCLC usually metastasizes widely very early on in the natural history of the tumor, and because nearly all cases respond dramatically to chemotherapy and/or radiotherapy, there has been little role for surgery in this disease since the 1970s. However, recent work suggests that in cases of small, asymptomatic, node-negative SCLC's ("very limited stage"), surgical excision may improve survival when used prior to chemotherapy ("adjuvant chemotherapy").

The tumor must be removed with as complete a surgical excision as possible. In nearly all cases, the ossicular chain must be included if recurrences are to be avoided. Due to the anatomic site of involvement, facial nerve paralysis and/or paresthesias may be seen or develop; this is probably due to mass effect rather than nerve invasion. In a few cases, reconstructive surgery may be required. Since this is a benign tumor, no radiation is required. Patients experience an excellent long term outcome, although recurrences can be seen (up to 15%), especially if the ossicular chain is not removed. Although controversial, metastases are not seen in this tumor. There are reports of disease in the neck lymph nodes, but these patients have also had other diseases or multiple surgeries, such that it may represent iatrogenic disease.

Patients treated with complete surgical excision can expect an excellent long term outcome without any problems. Recurrences may be seen in tumors which are incompletely excised.

The U.S. Food and Drug Administration granted in March 2017 an accelerated approval to the checkpoint-inhibitor avelumab for the treatment of adults and pediatric patients 12 years and older with metastatic Merkel cell carcinoma (MCC). This is the first FDA-approved treatment for metastatic MCC. Avelumab targets the PD-1/PD-L1 pathway (proteins found on the body’s immune cells and some cancer cells). By blocking these interactions, avelumab may help the body’s immune system attack cancer cells.

Prior to reaching the advanced stages of colorectal cancer, the polyps are confined to the inner wall and thickness of the intestinal tract and do not metastasize or 'spread'. So provided FAP is detected and controlled either at the pre-cancerous stage or when any cancerous polyps are still internal to the intestinal tract, surgery has a very high success rate of preventing or removing cancer, without recurrence, since the locations giving rise to cancer are physically removed "in toto" by the surgery.

Following surgery, if a partial colectomy has been performed, colonoscopic surveillance of the remaining colon is necessary as the individual still has a risk of developing colon cancer. However, if this happened, it would be a fresh incident from polyps developing anew in the unremoved part of the colon subsequent to surgery, rather than a return or metastasis of any cancer removed by the original surgery.

Because of its rarity, there have been no randomized clinical trials of treatment of GCCL, and all information available derives from small retrospective institutional series or multicenter metadata.

CUP is a term that refers to many different cancers. For that reason, treatment depends on where the cancer is found, the microscopic appearance of the cancer cells, the biochemical characterization of the cells, and the patient’s age and overall physical condition. In women, who present with axillary lymph node involvement, treatment is offered along the lines of breast cancer. In patients, who have neck lymph node involvement, then treatment is offered along the lines of head and neck cancer. If inguinal lymph nodes are involved, then treatment may be offered along the lines of genitourinary cancer.

If the site of origin is unknown or undiscovered, then the histology of the tumor (e.g., adenocarcinoma, squamous cell or mesenchymal) can usually be identified, and a probable origin may be assumed. When this is possible, then treatment is based on the type of cell and probable origin. Based on histological subtype, combination chemotherapy may be selected. A combination of carboplatin and paclitaxel is often used. Advances techniques such as FISH and tissue of origin testing may also be employed. Germ cell tumors often carry abnormality of chromosome 12, which if identified, directs treatment for metastatic germ cell tumors.

No method is standard for all forms of CUP, but chemotherapy, radiation therapy, hormone therapy, and surgery may be used alone or in combination to treat patients who have CUP. Even when the cancer is unlikely to be cured, treatment may help the patient live longer or improve the patient’s quality of life. Radiation may be used to shrink a variety of local tumors. However, the potential side effects of the treatment must be considered along with the potential benefits.

In CUP to secondary neck nodes, surgery followed by external beam radiotherapy is sufficient.

For CUP with an unfavorable prognosis, treatment with taxanes may provide a slight survival benefit. The uncertainties and ambiguity inherent in a CUP diagnosis may cause additional stress for the patient.

Based on overall cancer staging into stages I to IV, papillary thyroid cancer has a 5-year survival rate of 100 percent for stages I and II, 93 percent for stage III and 51 percent for stage IV.

There is increased life-time risk of secondary cancers (relative risk 3.63), with a slightly increased mortality risk (1.21) according to a 2004 Swedish study of 481 patients.

Several drugs that target molecular pathways in lung cancer are available, especially for the treatment of advanced disease. Erlotinib, gefitinib and afatinib inhibit tyrosine kinase at the epidermal growth factor receptor. Denosumab is a monoclonal antibody directed against receptor activator of nuclear factor kappa-B ligand. It may be useful in the treatment of bone metastases.