傳統的全身性化學治療，藥物打入血管中，隨著血液循環流動到身體各部位，並滲透到組織中。即使是口服化學治療藥物也是屬於全身性化學治療的一種。其中共同的缺點，就是藥物到達腹腔中的濃度都很低，對於轉移到腹腔中的癌細胞，毒殺作用非常有限。
而腹腔內的化學治療，因為腹腔內的濃度很高，對於轉移到腹腔中的癌細胞，毒殺效果較好。然而對於存在組織中的癌腫瘤，毒殺作用也非常有限。
如果腹腔轉移的癌細胞已經播種附著在腹膜或腸系膜或任何器官表面，經過一段時間的生長，會生長(向下扎根)到深層組織，而同時存在腹腔表面及組織深部的現象。這時候不論是單獨使用腹腔內化療(毒殺暴露於腹腔表面的腫瘤部分)或全身性化療(毒殺在組織中的腫瘤部分)，都無法達到滿意的效果。相反的，這時候如果同時使用腹腔內化療合併全身性化療，預計將可以達到較理想的治療效果。這種方式就是內外夾攻的概念，就稱為雙向性化學治療(Bidirectional Chemotherapy)。
如果疾病在初診斷時，就已經是比較嚴重的腹腔轉移狀態，也無法利用腫瘤減量手術(CRS)合併腹腔熱化療(HIPEC)達到理想狀態，我們就會利用雙向性化學治療，待狀況改善後，再實施腫瘤減量手術(CRS)合併腹腔熱化療(HIPEC)。這時候的雙向性化學治療，又稱為雙向性誘導化學治療 (Bidirectional Intraperitoneal and Systemic Induction Chemotherapy, BISIC)。
然而也不是每位病人都有機會接受雙向性化學治療。如果腹腔內腫瘤生長太過於嚴重，無法讓腹腔內化療的藥物順利滲透到所有腹腔表面，則治療效果一定不好，就不一定要接受雙向性化學治療。而接受雙向性誘導化學治療之後，如果腫瘤反應不佳，也無法進一步接受腫瘤減量手術 (CRS) 合併腹腔熱化療(HIPEC)。
我們目前已利用此方式實施於一些病人。其中有幾位病人都是原先被一些醫院認定為無法治療，經過雙向性誘導化學治療後，順利接受腫瘤減量手術 (CRS) 合併腹腔熱化療 (HIPEC)，目前皆無再發現象，狀況相當理想。
2023.07.06更新
胃癌雙向化療的最新成果
對於胃癌合併有腹腔內轉移的病人，過去的治療一向以全身性的化療為主。萬芳醫院熱化療團隊率先於2000年開始施行腫瘤減量手術合併腹腔熱化療，又於2013年起引入雙向化療方法來治療這一類的患者。因為部分病人的病情控制理想，2014年起則列入我們的優先選項。 我們將這8年來的治療結果做了初步分析，描述摘要如下。 （以下內容於2023年3月19日台灣外科聯合醫學會中發表） 1. 雙向化療前病人的腹腔內癌指數（PCI）為24。 2. 大約有40%的病人接受雙向化療以後，病情受到控制並且可以接受手術治療。 3. 將近30%的病人，雖然接受雙向化療，但是病情持續惡化。 4. 有20%的病人持續接受雙向化療後，其中部分的病人病情進步並且可以接受手術治療。 5. 可以接受手術治療的病人當中，如果能夠達到完全清除腫瘤或者讓殘留腫瘤小於0.25公分，預後最佳。中點存活期為12個月，最久已經超過6年。 6. 如果接收雙向化療以後腹腔內癌指數能降到12以下，則接受手術治療的機會相當高。 7. 全部併發症發生率為21%，嚴重併發症為3.5%，最多的併發症是傷口感染以及肺炎。
In traditional systemic chemotherapy, the drugs were given into the blood vessels and were transport to every part of the body, then into the organs and tissues. Oral intake of chemotherapeutic agent, is also a form of systemic chemotherapy. In systemic chemotherapy, the concentration of these drugs is very low in the peritoneal cavity. This makes a poor result of cytotoxic effect to the cancer cells within the peritoneal cavity.
In intraperitoneal chemotherapy, the drug concentrations within the peritoneal cavity is very high, which makes a significant cytotoxic effect to the cancer cells within the peritoneal cavity. However, the drugs within the peritoneal cavity was poorly absorbed into tissues, the cytotoxic effect to the cancers within the tissue is very poor.
Once the intraperitoneal cancer cells implant at the peritoneal surface, mesenteric surface or organ surface, after a period, these cancers will invade into the tissue and continue to grow into the deep tissues. It is, the cancers are present in the deep tissues and present at the peritoneal surface. In this condition, to use intraperitoneal chemotherapy alone (to kill the peritoneal surface cancers) or to use systemic chemotherapy alone (to kill the deep tissue cancers), will not reach a satisfied result.
However, if we use intraperitoneal chemotherapy as well as systemic chemotherapy simultaneously, a better result is predicted. It is killing cancers from outside and inside of the tissues, and is also called bidirectional chemotherapy.
If severe peritoneal metastasis is noted at the initial diagnosis, it is impossible to perform cytoreduction surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC), we can apply bidirectional chemotherapy first. After a few cycles of bidirectional chemotherapy, if the disease condition improved, then we can perform CRS and HIPEC. In this condition, the bidirectional chemotherapy is also called BISIC (Bidirectional Intraperitoneal and Systemic Induction Chemotherapy)。
However, not every patient is suitable for bidirectional chemotherapy. If the disease is too far advanced, the infused intraperitoneal drugs cannot be distributed evenly within the peritoneal cavity, the result of intraperitoneal chemotherapy will be limited. Bidirectional chemotherapy is not suitable for this condition. Furthermore, after a few cycles of bidirectional chemotherapy, if the disease condition is not improved, then CRS and HIPEC are not indicated.
We applied BISIC in some cases. They were suggested to receive palliative or supportive care by other physicians at other hospitals. After a few cycles of BISIC, some of them received CRS and HIPEC smoothly and survived till now without any evidence of disease recurrence. This is an encouraging fact to us.
2023.07.06 update
Recent results of bidirectional chemotherapy for gastric cancer
For patients with gastric cancer and intra-peritoneal metastases, the past treatment has been mainly systemic chemotherapy. The HIPEC team of Wanfang Hospital first began to perform cytoreduction surgery combined with HIPEC in 2000, and introduced bidirectional chemotherapy to treat such patients in 2013. Because some patients are well controlled, they have been on our top priority since 2014. We have made a preliminary analysis of the treatment results over the past 8 years, and the description is summarized below. (The following content was presented at the Annual Meeting of Taiwan Surgical Association on March 19, 2023) 1. The patient's peritoneal cancer index (PCI) before bidirectional chemotherapy was 24. 2. About 40% of patients who receive bidirectional chemotherapy are under control and can be treated with surgery. 3. Nearly 30% of patients receive bidirectional chemotherapy but continue to deteriorate. 4. After 20% of patients continue to receive bidirectional chemotherapy, some of them improved and can be treated with surgery. 5. Among patients who can undergo surgery, the prognosis is better if they can achieve complete tumor removal or residual tumor less than 0.25 cm. Median survival is 12 months, and the longest has been more than 6 years. 6. If the PCI drops below 12 after receiving bidirectional chemotherapy, the chances of receiving surgery are quite high. 7. The overall complication rate was 21%, with serious complications 3.5%, with the most common complications being wound infection and pneumonia.